Piezotronic effect in AlGaN/AlN/GaN heterojunction nanowires used as a flexible strain sensor

• Jianqi Dong,
• Liang Chen,
• Yuqing Yang and
• Xingfu Wang

Beilstein J. Nanotechnol. 2020, 11, 1847–1853, doi:10.3762/bjnano.11.166

• synthesize AlGaN/AlN/GaN heterojunction NWs with controllable size. A single NW is transferred to a flexible poly(ethylene terephthalate) substrate and fixed by indium tin oxide electrodes to form an ohmic contact for the strain sensor. An external mechanical stress is introduced to study the performance of

• introduced during the epitaxial growth process [1][2][3]. Furthermore, the analysis of the internal polarization of the AlGaN/AlN/GaN heterojunction showed the existence of a 2D electron gas (2DEG), which effectively suppresses the degradation of the carrier mobility caused by the scattering at charge

• polarization distribution inside the heterojunction [7][8]. The piezotronic effect, described first by Zhong Lin Wang in 2007, is a combination of the piezoelectric effect and the properties of non-centrosymmetric semiconductor materials [9]. 1D semiconductor nanowires (NWs) are more suitable candidates for

A self-powered, flexible ultra-thin Si/ZnO nanowire photodetector as full-spectrum optical sensor and pyroelectric nanogenerator

• Liang Chen,
• Jianqi Dong,
• Miao He and
• Xingfu Wang

Beilstein J. Nanotechnol. 2020, 11, 1623–1630, doi:10.3762/bjnano.11.145

• PD based on a p-Si/n-ZnO NWs heterojunction is illustrated in Figure 1a. A typical cross-sectional scanning electron microscopy (SEM) image of the as-grown Si/ZnO NWs heterojunction is shown in Figure 1b. The uniformly grown ZnO NWs are conducive to a stable short-circuit current output. The detailed

• -cycle dynamic response curve extracted from Figure 1c is shown in Figure 1d, indicating that the PD possesses a fast response speed (rising time τr = 18 μs, falling time τf = 25 μs). It is obvious that the p-Si/n-ZnO NWs heterojunction PDs exhibit excellent detection capability and work well without an

• external power source. Working mechanism of a PENG based on p-Si/n-ZnO NWs heterojunctions To illustrate the working mechanism of self-powered PDs, schematic diagrams for the different conditions are presented in Figure 2. In the dark, a depletion layer is formed at the heterojunction interface due to

High-responsivity hybrid α-Ag₂S/Si photodetector prepared by pulsed laser ablation in liquid

• Raid A. Ismail,
• Hanan A. Rawdhan and
• Duha S. Ahmed

Beilstein J. Nanotechnol. 2020, 11, 1596–1607, doi:10.3762/bjnano.11.142

• . synthesized monodisperse Ag2S NPs by using a sonochemical method and fabricated photodetector devices by integrating Ag2S NPs on a graphene sheet [17]. Tretyakov et al. [18] reported the characterization of a Ag2SQD (quantum dots)/Si heterojunction photodetector used for short-wave infrared radiation

• Ag2S nanoparticles, while the origin of carbon is CTAB. Hall measurement revealed that the Ag2S had a negative Hall coefficient, indicating that it is an n-type semiconductor. This finding agrees well with [39]. Figure 11 shows the dark I–V characteristics of an n-Ag2S/p-Si heterojunction prepared

• without and with CTAB under forward and reverse current flow. The forward current flow increased exponentially with bias voltage for the Ag2S/Si heterojunction synthesized in the presence of the CTAB surfactant, indicating the dominance of diffusion current. In the case of the heterojunction prepared

A wideband cryogenic microwave low-noise amplifier

• Boris I. Ivanov,
• Dmitri I. Volkhin,
• Ilya L. Novikov,
• Dmitri K. Pitsun,
• Dmitri O. Moskalev,
• Ilya A. Rodionov,
• Evgeni Il’ichev and
• Aleksey G. Vostretsov

Beilstein J. Nanotechnol. 2020, 11, 1484–1491, doi:10.3762/bjnano.11.131

• heterojunction bipolar technology (HBT). Recently, it has been shown that cryogenic amplifiers based on SiGe HBT [16][17][18] can provide low noise levels and high gain at 4 K. They are suitable for superconducting qubit readout [25][26] and radio astronomy systems [12][14]. In order to obtain high gain values

Cryogenic low-noise amplifiers for measurements with superconducting detectors

• Ilya L. Novikov,
• Boris I. Ivanov,
• Dmitri V. Ponomarev and
• Aleksey G. Vostretsov

Beilstein J. Nanotechnol. 2020, 11, 1316–1320, doi:10.3762/bjnano.11.115

• mobility transistor (HEMT) technology and SiGe bipolar heterojunction technology (HBT). Low-frequency amplifiers are usually applied as first stage of SQUID readout electronics [11][12] or as the readout of cryogenic bolometers [13]. In both cases the amplifiers have a working temperature of 300 K. Modern

Nonadiabatic superconductivity in a Li-intercalated hexagonal boron nitride bilayer

• Kamila A. Szewczyk,
• Izabela A. Domagalska,
• Artur P. Durajski and
• Radosław Szczęśniak

Beilstein J. Nanotechnol. 2020, 11, 1178–1189, doi:10.3762/bjnano.11.102

• nontoxic. It is worth noting that graphene on a hBN substrate was used to fabricate transistor devices with high mobility [35], with the help of which the quantum Hall effect was observed. A heterojunction with two graphene layers [30] and superlattice structures [36][37][38] were also constructed. The

• graphene/hBN heterojunction devices allowed for the detection of the Hofstadter’s butterfly phenomenon [39][40]. In both layer and bulk form, hBN has a large bandgap energy, which makes it an insulator [13][41]. Therefore, for a long time this material was not associated with superconductivity. The

Band tail state related photoluminescence and photoresponse of ZnMgO solid solution nanostructured films

• Vadim Morari,
• Aida Pantazi,
• Nicolai Curmei,
• Vitalie Postolache,
• Emil V. Rusu,
• Marius Enachescu,
• Ion M. Tiginyanu and
• Veaceslav V. Ursaki

Beilstein J. Nanotechnol. 2020, 11, 899–910, doi:10.3762/bjnano.11.75

• demonstrated on p-type Si [2][4] because p-type doping is still a big challenge to ZnO-based semiconductors. Liang et al. demonstrated a ZnMgO/p-Si heterojunction solar-blind UV photodetector with a BeO buffer layer [35]. In terms of the crystal structure of ZnMgO films used in photodetectors, three types of

• I ∝ Un, according to the Lampert theory [51]. For the heterojunction with a Zn0.9Mg0.1O film in the dark, the n value is about 4, while it becomes equal to 2 under illumination, which corresponds to the space charge limited (SCL) current injection according to the Mott–Gurney (MG) law [52]. For the

• heterojunction with a Zn0.6Mg0.4O film, the current–voltage characteristics fit to the MG law both in the dark and under illumination (see Figure 10c). These observations suggest that the investigated heterojunctions work at forward bias as injection photodiodes [53][54]. A more detailed investigation of

Effect of Ag loading position on the photocatalytic performance of TiO₂ nanocolumn arrays

• Jinghan Xu,
• Yanqi Liu and
• Yan Zhao

Beilstein J. Nanotechnol. 2020, 11, 717–728, doi:10.3762/bjnano.11.59

• theoretical optimal structure of the plasma metal–semiconductor heterojunction. Having this background in mind, we decided to prepare a TiO2 nanocolumn (TNC) structure by using AAO in combination with ALD, in which Ag particles could be selectively supported separately outside and inside the nanocolumns. Most

Effect of substitutional defects on resonant tunneling diodes based on armchair graphene and boron nitride nanoribbons lateral heterojunctions

• Majid Sanaeepur

Beilstein J. Nanotechnol. 2020, 11, 688–694, doi:10.3762/bjnano.11.56

• heterojunction; armchair boron nitride nanoribbon (ABNNR); armchair graphene nanoribbon (AGNR); negative differential resistance (NDR); nonequilibrium Green’s function (NEGF); resonant tunneling diode (RTD); substitutional defects; Introduction 2D materials have gained tremendous research interest due to the

Preparation, characterization and photocatalytic performance of heterostructured CuO–ZnO-loaded composite nanofiber membranes

• Wei Fang,
• Liang Yu and
• Lan Xu

Beilstein J. Nanotechnol. 2020, 11, 631–650, doi:10.3762/bjnano.11.50

• narrow direct bandgap of 1.2–1.79 eV [14]. Because of that, CuO is usually used in combination with large-bandgap semiconductors, such as ZnO and TiO2, in order to improve their photocatalytic activity under solar light irradiation [15]. It was reported that the p–n heterojunction between ZnO and CuO has

Implementation of data-cube pump–probe KPFM on organic solar cells

• Benjamin Grévin,
• Olivier Bardagot and
• Renaud Demadrille

Beilstein J. Nanotechnol. 2020, 11, 323–337, doi:10.3762/bjnano.11.24

• single-point mode or over a 2D grid. The spectroscopic data are acquired in open z-loop configuration, which simplifies the pp-KPFM operation. The validity of the implementation is probed by measurements using electrical pumping. The dynamical photoresponse of a bulk heterojunction solar cell based on

Molecular architectonics of DNA for functional nanoarchitectures

• Debasis Ghosh,
• Lakshmi P. Datta and
• Thimmaiah Govindaraju

Beilstein J. Nanotechnol. 2020, 11, 124–140, doi:10.3762/bjnano.11.11

• (II)-bis(cyclen)–NDI and Zn(II)-bis(cyclen)–DPP, were decorated using oligothymidine (dT40) as a scaffold via interaction of Zn(II)-bis(cyclen) with thymidine residues. The ensemble behaved as a donor–acceptor heterojunction system where DPP acted as a donor moiety and NDI as an acceptor moiety. One

Polyvinylpyrrolidone as additive for perovskite solar cells with water and isopropanol as solvents

• Chen Du,
• Shuo Wang,
• Xu Miao,
• Wenhai Sun,
• Yu Zhu,
• Chengyan Wang and
• Ruixin Ma

Beilstein J. Nanotechnol. 2019, 10, 2374–2382, doi:10.3762/bjnano.10.228

• primarily due to the suitability of PVP as an additive to enhance the photoelectric performance. Using PVP as an interlayer between the [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) electron transport layer (ETL) and the Ag cathode in a high-performance inverted planar heterojunction perovskite solar

Nontoxic pyrite iron sulfide nanocrystals as second electron acceptor in PTB7:PC₇₁BM-based organic photovoltaic cells

• Olivia Amargós-Reyes,
• José-Luis Maldonado,
• Omar Martínez-Alvarez,
• María-Elena Nicho,
• José Santos-Cruz,
• Juan Nicasio-Collazo,
• Irving Caballero-Quintana and
• Concepción Arenas-Arrocena

Beilstein J. Nanotechnol. 2019, 10, 2238–2250, doi:10.3762/bjnano.10.216

• of these NCs incorporated into the PTB7:PC71BM active layer of bulk-heterojunction ternary organic photovoltaic (OPV) cells. The OPV devices are fabricated with the direct configuration glass/ITO/PEDOT:PSS/PTB7:PC71BM:FeS2/PFN/FM. The Field’s metal (FM) is a eutectic alloy composed of 32.5% Bi, 51

• inside the CdS/CdTe inorganic heterojunction improved the conversion efficiency of the PV device by up to 8% [19]. Moreover, FeS2 has also been used in perovskite solar cells as a hole transport layer (HTL) to reduce the fabrication cost, reaching efficiencies of up to 11.2% [20]. On the other hand, OPVs

• have obtained a PCE of ≈2% at a size of 2.52 × 0.52 m [25]. The bulk-heterojunction (BHJ) approach is the most promising configuration to enhance the interpenetrated interface area in OPVs. In previous works, OPVs based on poly(3-hexylthiophene) (P3HT) or poly(thieno[3,4-b]thiophene-co-benzodithiophene

Improved adsorption and degradation performance by S-doping of (001)-TiO₂

• Xiao-Yu Sun,
• Xian Zhang,
• Xiao Sun,
• Ni-Xian Qian,
• Min Wang and
• Yong-Qing Ma

Beilstein J. Nanotechnol. 2019, 10, 2116–2127, doi:10.3762/bjnano.10.206

• high photocatalytic activity [10]. However, Yu et al. demonstrated that an appropriate proportion of exposed (001) and (101) crystal faces, which forms a “surface heterojunction”, facilitates the separation of photo-generated carriers [8]. Consequently, this improves the photocatalytic performance

High-temperature resistive gas sensors based on ZnO/SiC nanocomposites

• Vadim B. Platonov,
• Marina N. Rumyantseva,
• Alexander S. Frolov,
• Alexey D. Yapryntsev and
• Alexander M. Gaskov

Beilstein J. Nanotechnol. 2019, 10, 1537–1547, doi:10.3762/bjnano.10.151

• an n–n heterojunction at the ZnO/SiC interface. Keywords: electrospinning; high temperature gas sensor; n–n heterojunction; ZnO/SiC nanocomposite; Introduction The risk of air pollution is growing due to the development of new technologies in the chemical, metallurgical and food industries, the use

• SiC content in nanocomposites (within the error, Table 1). The growth of the electrical resistance and Ea can be associated with an increase in the concentration of surface oxygen species (confirmed by XPS), which form different acceptor levels at the ZnO surface and at the ZnO/SiC heterojunction. The

• interpreted in the context of the assumption of the formation of an n–n heterojunction at the ZnO/SiC interface, resulting in electron transfer from SiC to ZnO. The increase in the concentration of electrons in the near-surface layer of ZnO leads to an increase in the concentration of chemisorbed oxygen on

Selective gas detection using Mn₃O₄/WO₃ composites as a sensing layer

• Yongjiao Sun,
• Zhichao Yu,
• Wenda Wang,
• Pengwei Li,
• Gang Li,
• Wendong Zhang,
• Lin Chen,
• Serge Zhuivkov and
• Jie Hu

Beilstein J. Nanotechnol. 2019, 10, 1423–1433, doi:10.3762/bjnano.10.140

• detection. The devices displayed different sensing responses toward different gases at specific temperatures. The gas sensing performance of Mn3O4/WO3 composites (especially at 3 atom % Mn) were far improved compared to sensors based on pure WO3, where the improvement is related to the heterojunction formed

• region and higher resistance in the atmosphere of air, which will facilitate an increased response (Figure 12c). Secondly, when p-type Mn3O4 is attached on the surface of n-type WO3, the p–n heterojunction is formed, which contributes to the increase of the resistance in air due to the thicker depletion

BiOCl/TiO₂/diatomite composites with enhanced visible-light photocatalytic activity for the degradation of rhodamine B

• Minlin Ao,
• Kun Liu,
• Xuekun Tang,
• Zishun Li,
• Qian Peng and
• Jing Huang

Beilstein J. Nanotechnol. 2019, 10, 1412–1422, doi:10.3762/bjnano.10.139

• lower than ordinary TiO2 (3.18 eV). The Eg of BTD decreases, obviously due to the formation of heterojunction structures in the composite, which is beneficial to visible light response. To further study the band structure of the composites, the Mott–Schottky curves were calculated and are plotted in

• composite exhibits excellent photocatalytic activity toward RhB degradation under visible-light irradiation. According to the characterization and analysis, the BTD composite has a heterojunction structure with an energy gap of 2.80 eV that can efficiently produce electrons and holes under illumination by

• visible light. Meanwhile, the heterojunction structure can promote the transfer of carriers, and can thus hinder the recombination of photogenerated electron–hole pairs. As a result, the photocatalytic activity is considerably improved. The BTD composite developed in this work has great application

Construction of a 0D/1D composite based on Au nanoparticles/CuBi₂O₄ microrods for efficient visible-light-driven photocatalytic activity

• Weilong Shi,
• Mingyang Li,
• Hongji Ren,
• Feng Guo,
• Xiliu Huang,
• Yu Shi and
• Yubin Tang

Beilstein J. Nanotechnol. 2019, 10, 1360–1367, doi:10.3762/bjnano.10.134

• heterojunction was formed in the composite photocatalyst. The chemical and electronic states of the elements on the Au/CBO surface were characterized by XPS. In the Au 4f XPS spectrum (Figure 5a) peaks at binding energies of 84.1 and 87.7 eV pertaining to Au 4f7/2 and Au 4f5/2, respectively, indicate that the

• toward the degradation of TC, and only 52% TC was degraded after 120 min. The 0D/1D Au/CBO heterojunction photocatalysts showed a significant improvement in photocatalytic performance, demonstrating that Au NPs play an important role in the composites during the photocatalytic process. With increasing Au

• ). Thus, O2 can be captured and reduced to •O2− to degrade TC, while the holes in the VB of CBO can directly oxidize TC [10], which is consistent with the results of the trapping experiments (Figure 8). To sum up, the construction of 0D/1D heterojunction is conducive to the effective separation of

Synthesis of novel C-doped g-C₃N₄ nanosheets coupled with CdIn₂S₄ for enhanced photocatalytic hydrogen evolution

• Jingshuai Chen,
• Chang-Jie Mao,
• Helin Niu and
• Ji-Ming Song

Beilstein J. Nanotechnol. 2019, 10, 912–921, doi:10.3762/bjnano.10.92

• , Huang et al. fabricated self-doped C-atom g-C3N4 via self-assembly, which exhibited highly efficient photocatalytic activity of H2 evolution under visible-light irradiation [22]. Moreover, the construction of a heterojunction composite is an effective approach to facilitate the separation of

• photocatalytic performance of CdIn2S4 alone is barely satisfactory, mainly due to the low separation and migration efficiency of photogenerated charge carriers. The construction of a heterojunction by combination with semiconductor materials is expected to be a strategy to improve the separation of

• samples were characterized by transmission electron microscopy (TEM) images. As can be seen in Figure 4a,b, the CCN sample displays a representative two-dimensional layered structure that is ultrathin. After the addition of CdIn2S4 to form the heterojunction with CCN, the CdIn2S4 crystals are attached to

Renewable energy conversion using nano- and microstructured materials

• Harry Mönig and
• Martina Schmid

Beilstein J. Nanotechnol. 2019, 10, 771–773, doi:10.3762/bjnano.10.76

• scattering can be tailored to give rise to field enhancement, path-length enhancement and finally increased absorption. Nano- and microtextures in Si heterojunction solar cells are addressed from a theoretical point of view in [3], whereas [5] additionally presents an experimental verification of the

• benefits arising from core–shell nanowire arrays for Si heterojunction solar cells. Contacts with a high surface-to-volume ratio can clearly be seen. Particularly in photovoltaics, they may be prone to increased recombination losses. For other applications, such as water splitting, porous materials may

Geometrical optimisation of core–shell nanowire arrays for enhanced absorption in thin crystalline silicon heterojunction solar cells

• Robin Vismara,
• Olindo Isabella,
• Andrea Ingenito,
• Fai Tong Si and
• Miro Zeman

Beilstein J. Nanotechnol. 2019, 10, 322–331, doi:10.3762/bjnano.10.31

• illumination conditions, by exciting resonances inside the absorber layer. However, passivation of nanowires is critical to further improve the efficiency of such devices. Keywords: heterojunction; nanowires; optical modelling; photovoltaics; silicon; Introduction The implementation of effective and low-cost

• ], and recently perovskite [38][39][40][41]. In this contribution, the performance of crystalline silicon (c-Si) nanowire arrays is investigated. The study is divided in two parts. First, a proof-of-concept device was realised, consisting of a heterojunction of amorphous silicon on a p-type c-Si nanowire

• array. The standard manufacturing procedure of c-Si heterojunction solar cells was followed, with the only addition of a cost-effective mask-less reactive ion etching step to create nanowires on the surface of the p-type Si wafer. The resulting 5 × 5 mm2 cell exhibits a best-device efficiency of 11.8

Uniform Sb₂S₃ optical coatings by chemical spray method

• Jako S. Eensalu,
• Atanas Katerski,
• Erki Kärber,
• Ilona Oja Acik,
• Arvo Mere and
• Malle Krunks

Beilstein J. Nanotechnol. 2019, 10, 198–210, doi:10.3762/bjnano.10.18

• (structured) window layer, Sb2S3 absorber layer, and hole transport material layer, and their respective interfaces, is a tremendous undertaking [4]. Attention has surged toward planar heterojunction Sb2S3 solar cells due to their simpler structure, less intricate production, and enhanced repeatability vs

Amorphous Ni_xCo_yP-supported TiO₂ nanotube arrays as an efficient hydrogen evolution reaction electrocatalyst in acidic solution

• Yong Li,
• Peng Yang,
• Bin Wang and
• Zhongqing Liu

Beilstein J. Nanotechnol. 2019, 10, 62–70, doi:10.3762/bjnano.10.6

• heterojunction can lower the band gap of the material thus augment the conductivity. The material band gap can be calculated by measuring the optical absorption edge in UV–vis DRS, shown in Figure 5f. It is observed that the absorption edge showed a red shift after electrodeposition of Ni–P and NiCoP. The

Graphene-enhanced metal oxide gas sensors at room temperature: a review

• Dongjin Sun,
• Yifan Luo,
• Marc Debliquy and
• Chao Zhang

Beilstein J. Nanotechnol. 2018, 9, 2832–2844, doi:10.3762/bjnano.9.264

• of the p–n heterojunction is shown in Figure 1, Ec and Ev are the energies of conduction band and valence band of the two components, respectively, while the Fermi level energy (Ef) is between these two bands. It can be seen from Figure 1 that the work function of rGO is lower than that of SnO2