scholarly journals Electron Scattering by Native Defects in Uniformly and Modulation Doped Semiconductor Structures

1989 ◽  
Vol 163 ◽  
Author(s):  
W. Walukiewicz
Keyword(s):  
Electron Scattering ◽  
Electron Mobility ◽  
Defect Formation ◽  
Hole Concentration ◽  
Defect Model ◽  
Free Electron Concentration ◽  
Defect Formation Energy ◽  
Native Defects ◽  
Semiconductor Structures ◽  
Heavily Doped

AbstractFormation of native defects in GaAs is described in terms of the amphoteric native defect model. It is shown that Fermi energy induced formation of gallium vacancies is responsible for the limitations of maximum free electron concentration in GaAs. The effect of the defects on electron mobility in heavily doped n-GaAs is quantitatively evaluated. Defect scattering explains the abrupt reduction of electron mobility at high doping levels. Also, it is demonstrated that native defects are responsible for the mobility reduction in inverted modulation doped GaAs/AlGaAs heterostructures. The amphoteric defect model also explains a distinct asymmetry in defect formation in n- and p-GaAs. In p-GaAs the Fermi level induced reduction of the defect formation energy is much smaller, and therefore the concentration of the native defects is negligible compared with the hole concentration.

Doping Limitation Due to Self-compensation by Native Defects in In-doped Rocksalt CdxZn1-xO

2021 ◽  
Author(s):  
Chun Yuen HO ◽  
Chia Hsiang Li ◽  
Chao Ping Liu ◽  
Zhi-Quan Huang ◽  
Feng-Chuan Chuang ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Band Gap ◽  
Electron Mobility ◽  
Density Functional ◽  
Defect Formation ◽  
Wide Band ◽  
High Electron ◽  
Transparent Conductor ◽  
Full Spectrum ◽  
Native Defects

Abstract CdO-ZnO alloys (CdxZn1-xO) exhibit a transformation from the wurtzite (WZ) to the rocksalt (RS) phase at a CdO composition of ~70% with a drastic change in the band gap and electrical properties. RS-CdxZn1-xO alloys (x>0.7) are particularly interesting for transparent conductor applications due to their wide band gap and high electron mobility. In this work, we synthesized RS-CdxZn1-xO alloys doped with different concentrations of In dopants and evaluated their electrical and optical properties. Experimental results are analyzed in terms of the amphoteric native defect model and compared directly to defect formation energies obtained by hybrid density functional theory (DFT) calculations. A saturation in electron concentration of ~7x1020cm-3 accompanied by a rapid drop in electron mobility is observed for the RS-CdxZn1-xO films with 0.7≤x<1 when the In dopant concentration [In] is larger than 3%. Hybrid DFT calculations confirm that the formation energy of metal vacancy acceptor defects is significantly lower in RS-CdxZn1-xO than in CdO, and hence limits the free carrier concentration. Mobility calculations reveal that due to the strong compensation by native defects, RS-CdxZn1-xO alloys exhibit a compensation ratio of >0.7 for films with x<0.8. As a consequence of the compensation by native defects, in heavily doped RS-CdxZn1-xO carrier-induced band filling effect is limited. Furthermore, the much lower mobility of the RS-CdxZn1-xO alloys also results in a higher resistivity and reduced transmittance in the near infra-red region (λ>1100 nm), making the material not suitable as transparent conductors for full spectrum photovoltaics.

scholarly journals Defect Reactions at Metal-Semiconductor and Semiconductor-Semiconductor Interfaces

1989 ◽  
Vol 148 ◽  
Author(s):  
W. Walukiewicz
Keyword(s):  
Fermi Level ◽  
Formation Energy ◽  
Defect Formation ◽  
Quantitative Description ◽  
Stabilization Energy ◽  
Defect Formation Energy ◽  
New Approach ◽  
Native Defects ◽  
Semiconductor Interfaces ◽  
Defect Reactions

ABSTRACTA recently proposed, new approach to the problem of native defect formation in compound semiconductors is presented. The approach is based on the concept of amphoteric native defects. It is shown that the defect formation energy as well as structure and properties of simple native defects depend on the location of the Fermi level with respect to an internal energy reference: the Fermi level stabilization energy. The known location of the stabilization energy determines the electronic part of the defect formation energy and allows for a quantitative description of a variety of phenomena including: the formation of defects at metal-semiconductor interfaces, doping induced superlattice intermixing and limitations of free carrier concentrations in semiconductors.

Model of Electron Scattering of Strained Si /Si1-xGex (100)

2011 ◽  
Vol 110-116 ◽  
pp. 3338-3342
Author(s):  
Jian Jun Song ◽  
Hua Ying Wu ◽  
He Ming Zhang ◽  
Hui Yong Hu ◽  
Heng Sheng Shan
Keyword(s):  
Electron Scattering ◽  
Electron Mobility ◽  
Acoustic Phonon ◽  
Golden Rule ◽  
Collision Term ◽  
Strained Si ◽  
Total Electron ◽  
Total Scattering ◽  
Scattering Rate ◽  
Term Approximation

Based on Fermi's golden rule and the theory of Boltzmann collision term approximation, taking into account all the scattering mechanisms contributed by ionized impurity, acoustic phonon and intervalley phonon, the model of total scattering rate of strained Si/(100) Si1-xGex is established. Simulating of the scattering models with Matlab software, it was found that the total scattering rate of electron in strained Si/(100) Si1-xGex decreases obviously with the increasing stress when Ge fraction x is less than 0.2 and the values continue to show a constant tendency, and that the total electron scattering rate of strained Si/(100) Si1-xGex decreases about 57% at most comparison with one of unstrained Si. The result can provide valuable references to the research of electron mobility of strained Si materials and the design of NMOS devices.

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