Design principle for a p-type oxide gate layer on AlGaN/GaN toward normally-off HEMTs: Li-doped NiO as a model

2020 ◽  
Vol 8 (3) ◽  
pp. 1125-1134
Author(s):  
Guanjie Li ◽  
Xiaomin Li ◽  
Junliang Zhao ◽  
Fawang Yan ◽  
Qiuxiang Zhu ◽  
...  
Keyword(s):  
Design Principle ◽  
Band Alignment ◽  
Key Factor ◽  
P Type ◽  
Gate Layer

The band alignment matching between p-type oxide and AlGaN/GaN is revealed to be key factor for p-type oxide gated normally-off HEMTs.

scholarly journals Optimal n-Type Al-Doped ZnO Overlayers for Charge Transport Enhancement in p-Type Cu2O Photocathodes

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 338
Author(s):  
Hak Hyeon Lee ◽  
Dong Su Kim ◽  
Ji Hoon Choi ◽  
Young Been Kim ◽  
Sung Hyeon Jung ◽  
...  
Keyword(s):  
Charge Transport ◽  
Atomic Layer ◽  
Absorption Efficiency ◽  
Open Circuit ◽  
Band Alignment ◽  
Conformal Coating ◽  
Layer Deposition ◽  
Layer Stacking ◽  
Doped Zno ◽  
P Type

An effective strategy for improving the charge transport efficiency of p-type Cu2O photocathodes is the use of counter n-type semiconductors with a proper band alignment, preferably using Al-doped ZnO (AZO). Atomic layer deposition (ALD)-prepared AZO films show an increase in the built-in potential at the Cu2O/AZO interface as well as an excellent conformal coating with a thin thickness on irregular Cu2O. Considering the thin thickness of the AZO overlayers, it is expected that the composition of the Al and the layer stacking sequence in the ALD process will significantly influence the charge transport behavior and the photoelectrochemical (PEC) performance. We designed various stacking orders of AZO overlayers where the stacking layers consisted of Al2O3 (or Al) and ZnO using the atomically controlled ALD process. Al doping in ZnO results in a wide bandgap and does not degrade the absorption efficiency of Cu2O. The best PEC performance was obtained for the sample with an AZO overlayer containing conductive Al layers in the bottom and top regions. The Cu2O/AZO/TiO2/Pt photoelectrode with this overlayer exhibits an open circuit potential of 0.63 V and maintains a high cathodic photocurrent value of approximately −3.2 mA cm−2 at 0 VRHE for over 100 min.

Interfacial defect engineering and Photocatalysis Properties of hBN/MX2(M = Mo, W, and X = S, Se) Heterostructures

2021 ◽  
Author(s):  
Zhihai Sun ◽  
Jiaxi Liu ◽  
Ying Zhang ◽  
Ziyuan Li ◽  
Leyu Peng ◽  
...  
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Band Alignment ◽  
Type I ◽  
Defect Engineering ◽  
Wide Range ◽  
Interfacial Defects ◽  
Significant Research ◽  
P Type ◽  
The Impact

Abstract Van der Waals (VDW) heterostructures have attracted significant research interest due to their tunable interfacial properties and potential in a wide range of applications such as electronics, optoelectronic, and heterocatalysis. In this work, the impact of interfacial defects on the electronic structures and photocatalytic properties of hBN/MX2(M = Mo, W, and X = S, Se) are studied using density functional theory calculations. The results reveal that the band alignment of hBN/MX2 can be adjusted by introducing vacancies and atomic doping. The type-I band alignment of the host structure was maintained in the heterostructure with n-type doping in the hBN sublayer. Interestingly, the band alignment changed to the type-II heterostructrue as VB defect and p-type doping was introduced in the hBN sublayer. This could be profitable for the separation of photo-generated electron−hole pairs at the interfaces and is highly desired for heterostructure photocatalysis. In addition, two Z-type heterostructures including hBN(BeB)/MoS2, hBN(BeB)/MoSe2, and hBN(VN)/MoSe2 were achieved, showing reducing band gap and ideal redox potential for water splitting. Our results reveal the possibility of engineering the interfacial and photocatalysis properties of hBN/MX2 heterostructures via interfacial defects.

scholarly journals Electronic properties of the Sn1−xPbxO alloy and band alignment of the SnO/PbO system: a DFT study

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
N. Kelaidis ◽  
S. Bousiadi ◽  
M. Zervos ◽  
A. Chroneos ◽  
N. N. Lathiotakis
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Hydrogen Generation ◽  
Valence Band Maximum ◽  
Oxide System ◽  
Band Alignment ◽  
Oxide Thin Film ◽  
Ternary Oxide ◽  
P Type

Abstract Tin monoxide (SnO) has attracted attention due to its p-type character and capability of ambipolar conductivity when properly doped, properties that are beneficial for the realization of complementary oxide thin film transistors technology, transparent flexible circuits and optoelectronic applications in general. However, its small fundamental band gap (0.7 eV) limits its applications as a solar energy material, therefore tuning its electronic properties is necessary for optimal performance. In this work, we use density functional theory (DFT) calculations to examine the electronic properties of the Sn1−xPbxO ternary oxide system. Alloying with Pb by element substitution increases the band gap of SnO without inducing defect states in the band gap retaining the anti-bonding character of the valence band maximum which is beneficial for p-type conductivity. We also examine the properties of the SnO/PbO heterojunction system in terms of band alignment and the effect of the most common intrinsic defects. A broken gap band alignment for the SnO/PbO heterojunction is calculated, which can be attractive for energy conversion in solar cells, photocatalysis and hydrogen generation.

The role of band alignment in p-type conductivity of Na-doped ZnMgO: Polar versus non-polar

2014 ◽  
Vol 104 (11) ◽  
pp. 112106 ◽  
Author(s):  
H. H. Zhang ◽  
X. H. Pan ◽  
Y. Li ◽  
Z. Z. Ye ◽  
B. Lu ◽  
...  
Keyword(s):  
Band Alignment ◽  
Type Conductivity ◽  
P Type

A type-II GeSe/SnS heterobilayer with a suitable direct gap, superior optical absorption and broad spectrum for photovoltaic applications

2017 ◽  
Vol 5 (26) ◽  
pp. 13400-13410 ◽  
Author(s):  
Congxin Xia ◽  
Juan Du ◽  
Wenqi Xiong ◽  
Yu Jia ◽  
Zhongming Wei ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Broad Spectrum ◽  
Band Alignment ◽  
Promising Material ◽  
Type Ii ◽  
Photovoltaic Applications ◽  
P Type

Type-II band alignment, a suitable direct gap (1.519 eV), superior optical-absorption (∼105) and a broad spectrum make the GeSe/SnS heterobilayer a promising material for photovoltaic applications.

Electronic Properties of GaN (0001) – Dielectric Interfaces

2004 ◽  
Vol 14 (01) ◽  
pp. 107-125 ◽  
Author(s):  
T. E. Cook ◽  
C. C. Fulton ◽  
W. J. Mecouch ◽  
R. F. Davis ◽  
G. Lucovsky ◽  
...  
Keyword(s):  
Electron Affinity ◽  
Photoelectron Spectroscopy ◽  
Band Alignment ◽  
Band Offset ◽  
Energy Bands ◽  
Interface Dipole ◽  
Conduction Band Offset ◽  
Dielectric Interfaces ◽  
P Type ◽  
Interface Type

The characteristics of clean n- and p-type GaN (0001) surfaces and the interface between this surface and SiO 2, Si 3 N 4, and HfO 2 have been investigated. Layers of SiO 2, Si3 N 4, or HfO 2 were carefully deposited to limit the reaction between the film and clean GaN surfaces. After stepwise deposition, the electronic states were measured with x-ray photoelectron spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS). A valence band offset (VBO) of 2.0±0.2 eV with a conduction band offset (CBO) of 3.6±0.2 eV was determined for the GaN / SiO 2 interface. The large band offsets suggest SiO 2 is an excellent candidate for passivation of GaN . For the GaN / Si 3 N 4, interface, type II band alignment was observed with a VBO of -0.5±0.2 eV and a CBO of 2.4±0.2 eV . While Si3 N 4 should passivate n-type GaN surfaces, it may not be appropriate for p-type GaN surfaces. A VBO of 0.3±0.2 eV with a CBO of 2.1±0.2 eV was determined for the annealed GaN / HfO 2 interface. An instability was observed in the HfO 2 film, with energy bands shifting ~0.4 eV during a 650°C densification anneal. The electron affinity measurements via UPS were 3.0, 1.1, 1.8, and 2.9±0.1 eV for GaN , SiO 2, Si 3 N 4, and HfO 2 surfaces, respectively. The deduced band alignments were compared to the predictions of the electron affinity model and deviations were attributed to a change of the interface dipole. Interface dipoles contributed 1.6, 1.1 and 2.0±0.2 eV to the band alignment of the GaN / SiO 2, GaN / Si 3 N 4, and GaN / HfO 2 interfaces, respectively. It was noted that the existence of Ga-O bonding at the heterojunction could significantly affect the interface dipole, and consequently the band alignment in relation to the GaN .

scholarly journals Band alignment and p -type doping of ZnSnN2

2017 ◽  
Vol 95 (20) ◽  
Author(s):  
Tianshi Wang ◽  
Chaoying Ni ◽  
Anderson Janotti
Keyword(s):  
Band Alignment ◽  
P Type

Synthesis and Characterization of Copper Oxide Compounds

2014 ◽  
Vol 1633 ◽  
pp. 3-12 ◽  
Author(s):  
K.P. Hering ◽  
A. Polity ◽  
B. Kramm ◽  
A. Portz ◽  
B.K. Meyer
Keyword(s):  
Copper Oxide ◽  
Photoelectron Spectroscopy ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Band Alignment ◽  
Synthesis And Characterization ◽  
Attractive Alternative ◽  
Oxide Compound ◽  
P Type

ABSTRACTThe p-type conducting Copper-oxide compound semiconductors (Cu2O, CuO) provide a unique possibility to tune the band gap energies from 2.1 eV to the infrared at 1.40 eV into the middle of the efficiency maximum for solar cell applications. By a pronounced non-stoichiometry the electronic properties may vary from insulating to metallic conduction. They appear to be an attractive alternative absorber material in terms of abundance, sustainability, non-toxicity of the elements, and numerous methods for thin film deposition that facilitate low cost production. The synthesis and characterization of Cu2O thin films used as p-type absorbers in heterojunction solar cells will be reported. We discuss properties of the undoped non-stoichiometric Cu2O, controlled p-type doping by nitrogen, analysis of band offsets by X-ray photoelectron spectroscopy (XPS). In addition we show proof of concept for an increase in photovoltaic conversion efficiency in AlGaN/Cu2O heterostructures due to a more favorable band alignment.

Drift velocity of holes in germanium and silicon

1979 ◽  
Vol 57 (8) ◽  
pp. 1233-1238 ◽  
Author(s):  
H. Nakagawa ◽  
S. Zukotynski
Keyword(s):  
Experimental Data ◽  
Drift Velocity ◽  
Coupling Constants ◽  
Phonon Coupling ◽  
Key Factor ◽  
Maxwellian Distribution Function ◽  
Valence Bands ◽  
P Type ◽  
Theoretical Results ◽  
Good Agreement

The displaced Maxwellian distribution function as it applies to semiconductors with lattice limited scattering is discussed. It is shown that good agreement between theoretical results and experimental data for the drift velocity can be obtained if the phonon coupling constants are lowered somewhat from their correct values. Calculations are presented for p-type germanium and silicon and it is shown that the key factor that must be considered in both materials is the non-parabolicity of the valence bands.

scholarly journals VLS Grown 4H-SiC Buried P+ Layers for JFET Lateral Structures

2015 ◽  
Vol 821-823 ◽  
pp. 789-792 ◽  
Author(s):  
Selsabil Sejil ◽  
Farah Laariedh ◽  
Mihai Lazar ◽  
Davy Carole ◽  
Christian Brylinski ◽  
...  
Keyword(s):  
Leakage Current ◽  
Vapor Liquid Solid ◽  
Selective Epitaxy ◽  
Transfer Length ◽  
P Type ◽  
Lateral Structures ◽  
Sic Wafer ◽  
Gate Layer ◽  
Vapor Liquid ◽  
Ion Implanted

Lateral JFET transistors have been fabricated with N and P-type channels tentatively integrated monolithically on the same SiC wafer. Buried P+SiC layers grown by Vapor-Liquid-Solid (VLS) selective epitaxy were utilized as source and drain for the P-JFET and as gate for the N-JFET. The ohmicity of the contacts, both on VLS grown P+and ion implanted N+layers, has been confirmed by Transfer Length Method (TLM) measurements. A premature leakage current is observed on the P/N junction created directly by the P+VLS gate layer, probably due to imperfect VLS (P+) / CVD (N+) SiC interface.

Sign in / Sign up

Export Citation Format

Share Document