P-Type Conductivity with a High Hole Mobility in Cubic GaN/GaAs Epilayers

1996 ◽  
Vol 449 ◽  
Author(s):  
D. J. As ◽  
A. Rüther ◽  
M. Lübbers ◽  
J. Mimkes ◽  
K. Lischka ◽  
...  
Keyword(s):  
Phonon Scattering ◽  
Theoretical Calculations ◽  
Hole Mobility ◽  
Growth Conditions ◽  
High Energy ◽  
Polar Optical Phonon ◽  
Temperature Dependent ◽  
Type Conductivity ◽  
Cubic Gan ◽  
P Type

ABSTRACTTemperature dependent Hall-Effect-measurements on unintentionally doped cubic GaN epilayers grown by molecular beam epitaxy (MBE) are reported. The cubic GaN layers have been deposited on semiinsulating (001) GaAs-substrates under N-stabilized growth conditions which were controlled by in-situ reflection high energy electron diffraction (RHEED) measurements. GaN-layers, which were fabricated under N-stabilized conditions have a (2×2) surface reconstruction during growth and show p-type conductivity. At room temperature the measured hole concentrations and mobilities are p = 9.7* 1012 cm-3, μp ≅ 350 cm2/Vs, respectively. Temperature dependent measurements of the carrier concentration yield an acceptor activation energy of EA = 0.445 eV. The nature of these defects will be discussed in view of intrinsic defects proposed by theoretical calculations already published in literature. The temperature dependence of the mobility is dominated by polar optical phonon scattering in the investigated temperature range.

Electrical and Optical Properties of Carbon Doped Cubic GaN Epilayers Grown Under Extreme Ga Excess

2003 ◽  
Vol 798 ◽  
Author(s):  
D. J. As ◽  
D. G. Pacheco-Salazar ◽  
S. Potthast ◽  
K. Lischka
Keyword(s):  
Optical Properties ◽  
Hole Concentration ◽  
Hole Mobility ◽  
Growth Conditions ◽  
Rf Plasma ◽  
Electrical And Optical Properties ◽  
Carbon Doped ◽  
Cubic Gan ◽  
Hall Effect Measurements ◽  
P Type

ABSTRACTP-type doping of cubic GaN by carbon is reported with maximum hole concentration of 2 6.1×1018cm-3and hole mobility of 23.5 cm /Vs at room temperature, respectively. The cubic GaN:C was grown by rf-plasma assisted molecular beam epitaxy (MBE) under Ga-rich growth conditions on a semiinsulating GaAs (001) substrate (3 inches wafer). E-beam evaporation of a graphite rode with an C-flux of 1×1012cm-2s-1was used for C-doping of the c-GaN. Optical microscopy, Hall-effect measurements and photoluminescence were performed to investigate the morphological, electrical and optical properties of cubic GaN:C. Under Ga-rich growth conditions most part of the carbon atoms were incorporated substitutially on N-site giving p-type conductivity. Our results verify that effective p-type doping of c-GaN can be achieved under extrem Ga excess.

Temperature Dependent Quasi-Periodic Facetting of AlAs Grown by MBE on (100) GaAs Substrates

1993 ◽  
Vol 312 ◽  
Author(s):  
Richard Mirin ◽  
Mohan Krishnamurthy ◽  
James Ibbetson ◽  
Arthur Gossard ◽  
John English ◽  
...  
Keyword(s):  
Growth Conditions ◽  
High Energy ◽  
High Energy Electron ◽  
Temperature Dependent ◽  
Cross Sectional ◽  
Mbe Growth ◽  
Atomic Force ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Facet Formation

AbstractHigh temperature (≥ 650°C) MBE growth of AlAs and AlAs/GaAs superlattices on (100) GaAs is shown to lead to quasi-periodic facetting. We demonstrate that the facetting is only due to the AlAs layers, and growth of GaAs on top of the facets replanarizes the surface. We show that the roughness between the AlAs and GaAs layers increases with increasing number of periods in the superlattice. The roughness increases to form distinct facets, which rapidly grow at the expense of the (100) surface. Within a few periods of the initial facet formation, the (100) surface has disappeared and only the facet planes are visible in cross-sectional transmission electron micrographs. At this point, the reflection high-energy electron diffraction pattern is spotty, and the specular spot is a distinct chevron. We also show that the facetting becomes more pronounced as the substrate temperature is increased from 620°C to 710°C. Atomic force micrographs show that the valleys enclosed by the facets can be several microns long, but they may also be only several nanometers long, depending on the growth conditions.

scholarly journals Electrical Properties of Cubic InN And GaN Epitaxial Layers as a Function of Temperature

2000 ◽  
Vol 5 (S1) ◽  
pp. 216-222
Author(s):  
J.R.L. Fernandez ◽  
V.A. Chitta ◽  
E. Abramof ◽  
A. Ferreira da Silva ◽  
J.R. Leite ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electrical Properties ◽  
Carrier Concentration ◽  
Doping Level ◽  
Type Conductivity ◽  
Si Doping ◽  
Donor And Acceptor ◽  
Cubic Gan ◽  
Si Doped ◽  
P Type

Carrier concentration and mobility were measured for intrinsic cubic InN and GaN, and for Si-doped cubic GaN as a function of temperature. Metallic n-type conductivity was found for the InN, while background p-type conductivity was observed for the intrinsic GaN layer. Doping the cubic GaN with Si two regimes were observed. For low Si-doping concentrations, the samples remain p-type. Increasing the Si-doping level, the background acceptors are compensated and the samples became highly degenerated n-type. From the carrier concentration dependence on temperature, the activation energy of the donor and acceptor levels was determined. Attempts were made to determine the scattering mechanisms responsible for the behavior of the mobility as a function of temperature.

DEFECT PHYSICS AND INTRINSIC p-TYPE CONDUCTIVITY IN TOPOLOGICAL INSULATOR AuTlS2

2014 ◽  
Vol 28 (02) ◽  
pp. 1450008 ◽  
Author(s):  
JIAN-MIN ZHANG ◽  
WANGXIANG FENG ◽  
PEI YANG ◽  
LIJIE SHI ◽  
YING ZHANG
Keyword(s):  
Point Defects ◽  
Topological Insulator ◽  
First Principles ◽  
Optimal Growth ◽  
Growth Conditions ◽  
First Principles Calculations ◽  
Type Conductivity ◽  
Native Point Defects ◽  
P Type ◽  
Optimal Growth Condition

Using first-principles calculations, we systematically investigate the defect physics in topological insulator AuTlS 2. An optimal growth condition is explicitly proposed to guide for the experimental synthesis. The stabilities of various native point defects under different growth conditions and different carrier environments are studied in detail. We show that the p-type conductivity is strongly preferred in AuTlS 2, and the band gap can be engineered by the control of intrinsic defects. Our results demonstrate that AuTlS 2 is an ideal p-type topological insulator which can be easily integrated with traditional semiconductor.

scholarly journals Prediction of higher thermoelectric performance in BiOCuSe by weakening electron-polar optical phonon scattering

2020 ◽  
Author(s):  
Tianqi Zhao ◽  
Quinn Gibson ◽  
Luke Daniels ◽  
Ben Slater ◽  
Furio Cora
Keyword(s):  
Carrier Mobility ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Hole Mobility ◽  
Polar Optical Phonon ◽  
First Principles Calculations ◽  
Thermoelectric Figure ◽  
Optical Phonon Scattering ◽  
Electron Phonon Scattering

Abstract BiOCuSe is a promising thermoelectric material, but its applications are hindered by low carrier mobility. We use first principles calculations to analyse electron-phonon scattering mechanisms and evaluate their contributions to the thermoelectric figure of merit ZT. The combined scattering of carriers by polar optical (PO) and longitudinal acoustic (LA) phonons yields an intrinsic hole mobility of 32 cm2 V-1 s-1 at room temperature and a temperature power law of T-1.5, which agree well with experiments. We demonstrate that electron phonon scattering in the Cu-Se layer dominates at low T, while contributions from the Bi-O layer become increasingly significant at higher T. At room temperature, ZT is calculated to be 0.48 and can be improved by 30% through weakening PO phonon scattering in the Cu-Se layer. This finding agrees with the experimental observation that weakening the carrier-phonon interaction by Te substitution in the Cu-Se layer improves mobility and ZT. At high T, the figure of merit is improved by weakening phonon scattering in the Bi-O layer instead. The theoretical ZT limit of BiOCuSe is calculated to be 2.5 at 875 K.

scholarly journals Higher thermoelectric performance of Zintl phases (Eu0.5Yb0.5)1−xCaxMg2Bi2 by band engineering and strain fluctuation

2016 ◽  
Vol 113 (29) ◽  
pp. E4125-E4132 ◽  
Author(s):  
Jing Shuai ◽  
Huiyuan Geng ◽  
Yucheng Lan ◽  
Zhuan Zhu ◽  
Chao Wang ◽  
...  
Keyword(s):  
Density Functional ◽  
Phonon Scattering ◽  
Theoretical Calculations ◽  
Thermoelectric Performance ◽  
Partial Substitution ◽  
Zintl Phases ◽  
Band Engineering ◽  
Transmission Electron ◽  
P Type ◽  
Callaway Model

Complex Zintl phases, especially antimony (Sb)-based YbZn0.4Cd1.6Sb2 with figure-of-merit (ZT) of ∼1.2 at 700 K, are good candidates as thermoelectric materials because of their intrinsic “electron–crystal, phonon–glass” nature. Here, we report the rarely studied p-type bismuth (Bi)-based Zintl phases (Ca,Yb,Eu)Mg2Bi2 with a record thermoelectric performance. Phase-pure EuMg2Bi2 is successfully prepared with suppressed bipolar effect to reach ZT ∼ 1. Further partial substitution of Eu by Ca and Yb enhanced ZT to ∼1.3 for Eu0.2Yb0.2Ca0.6Mg2Bi2 at 873 K. Density-functional theory (DFT) simulation indicates the alloying has no effect on the valence band, but does affect the conduction band. Such band engineering results in good p-type thermoelectric properties with high carrier mobility. Using transmission electron microscopy, various types of strains are observed and are believed to be due to atomic mass and size fluctuations. Point defects, strain, dislocations, and nanostructures jointly contribute to phonon scattering, confirmed by the semiclassical theoretical calculations based on a modified Debye–Callaway model of lattice thermal conductivity. This work indicates Bi-based (Ca,Yb,Eu)Mg2Bi2 is better than the Sb-based Zintl phases.

IMPROVEMENT IN MOBILITY AND CONDUCTIVITY OF FEW-LAYER MoS2 FILMS

2014 ◽  
Vol 28 (04) ◽  
pp. 1450028 ◽  
Author(s):  
XIYING MA ◽  
JIE HE ◽  
KANGYE CHEN ◽  
LA LIN
Keyword(s):  
High Efficiency ◽  
Phonon Scattering ◽  
Quartz Substrate ◽  
Metal Sulfide ◽  
Chemical Vapor ◽  
Charge Carrier Mobility ◽  
Characteristic P ◽  
Type Conductivity ◽  
P Type ◽  
Quartz Substrates

We present a study of the influence of annealing and doping on the electrical properties of few-layer (FL) MoS 2 films on Si and quartz substrates deposited using a self-designed metal sulfide chemical vapor deposition (MSCVD) system. FL MoS 2 slices obtained through MSCVD, in the size range of 50–200 nm, were found to be uniformly scattered on the substrates. The conductivity and mobility of these films are greatly enhanced after annealing at 650–850°C. The largest mobility measured for pure MoS 2 on quartz substrate is 6.4×103 cm 2/ Vs , almost two orders of magnitude larger than that of bulk MoS 2 (500 cm2/Vs). We deduce that the superior charge carrier mobility in our sample is mainly attributed to reduced phonon scattering because of a lower carrier density (1010-1011 cm -2) compared to previously documented values (1012-1013 cm -2). Additionally, the conductivity and carrier concentration of FL MoS 2 films were enhanced by about two orders of magnitude compared to those of the as-grown films doped with Cu , Na and Ag ions but not doped with B ions. The films doped with Na and Ag exhibit characteristic p-type conductivity, while those doped with Cu and B exhibit n-type conductivity. Moreover, the MoS 2/ Si heterojunction exhibited good rectification characteristics and excellent conductivity, indicating that the FL MoS 2 films will find many applications in high-efficiency nanodevices.

The n-type and p-type conductivity mechanisms of bulk BiOCl photocatalyst from hybrid density functional theory calculations

2021 ◽  
Author(s):  
Bo Kong ◽  
Tixian Zeng ◽  
Wentao Wang
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Growth Conditions ◽  
Hybrid Density Functional Theory ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Type Conductivity ◽  
P Type ◽  
Hybrid Density Functional

Abstract: In this work, the n-type and p-type conductivity mechanisms of bulk BiOCl are systematically investigated using first-principles calculations. Under the O-rich growth conditions, BiOCl presents the intrinsic p-type conductivity,...

High p‐type conductivity in cubic GaN/GaAs(113)A by using Be as the acceptor and O as the codopant

1996 ◽  
Vol 69 (18) ◽  
pp. 2707-2709 ◽  
Author(s):  
Oliver Brandt ◽  
Hui Yang ◽  
Helmar Kostial ◽  
Klaus H. Ploog
Keyword(s):  
Type Conductivity ◽  
Cubic Gan ◽  
P Type
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