Fermi-Level effect and junction carrier concentration effect on p-Type dopant distribution in IlI-V Compound superlattices

1998 ◽  
Vol 535 ◽  
Author(s):  
Chang-Ho Chen ◽  
Ulrich M. Gösele ◽  
Teh Y. Tan
Keyword(s):  
Electric Field ◽  
Fermi Level ◽  
Hole Concentration ◽  
Equilibrium Concentration ◽  
Dopant Atom ◽  
Group Iii ◽  
Atom Diffusion ◽  
Segregation Phenomenon ◽  
P Type ◽  
Positively Charged

AbstractThe pronounced segregation phenomenon in the distribution of p-type dopants Zn and Be in GaAs and related III-V compound heterostructures has been explained quantitatively by treating simultaneously the processes of dopant atom diffusion, segregation, and the effect of heterojunction carrier concentrations on these two aspects. Segregation of a dopant species between two semiconductor heterostructure layers is described by a model incorporating (i) a chemical effect on the neutral species; and (ii) in addition, a Fermi-level effect on the ionized species. The process of Zn and Be diffusion in GaAs and related compounds is governed by the doubly-positively-charged group III element self-interstitials whose thermal equilibrium concentration and hence also the Zn and Be diffusivities exhibit also a Fermi-level dependence, i.e., in proportion to p2.A heterojunction is consisting of a space charge region with an electric field, in which the hole concentration is different from those in the bulk layers. This influences the junction region concentrations of and of Zn− or Be−, which in turn influence the distribution of the ionized acceptor atoms. The overall process involves diffusion and segregation of holes, , Zn− or Be−, and an ionized interstitial acceptor species. The junction electric field also changes with time and position.

Effect of Fermi Level Pinning at the Surface During OMVPE Growth

1995 ◽  
Vol 378 ◽  
Author(s):  
R. M. Cohen ◽  
C. Y. Chen ◽  
W. M. Li ◽  
D. S. Simons ◽  
P. H. Chi
Keyword(s):  
Fermi Level ◽  
Fermi Energy ◽  
Growth Conditions ◽  
Ambient Conditions ◽  
Group Iii ◽  
Fermi Level Pinning ◽  
Zn Concentration ◽  
Excess Concentration ◽  
P Type ◽  
Positively Charged

AbstractDuring organometallic vapor phase epitaxy of GaAs, the Fermi energy is found to be pinned ≈200 meV below the intrinsic Fermi energy on a (lOO)-oriented surface. This was determined by making the first comparison of Zn concentration, Nzn. obtained from growth with that obtained at equilibrium, all under the same nominal ambient conditions. Donor solubility has been found to be virtually unchanged during growth of n- or p-type GaAs, and this is strong evidence that the Fermi level remains pinned at essentially the same energy during growth of n- or p-type GaAs. Consistent with Fermi level pinning, we find (1) the NZn is supersaturated in the epilayer for the ambient growth conditions used, (2) a large excess concentration of positively charged Ga interstitials can be grown into n-type GaAs and which diffuses into nearby p-type layers, causing (3) the Zn diffusivity, DZn ∼10−13 cm2/s, out of buried npn layers to be essentially independent of the ambient conditions. Annealing of a heavily Zn-doped layer at the surface can lead to 10−16<DZn<10−13 cm2/s at T=800°C simply by varying the Zn partial pressure over its commonly used range. Use of In-doped spikes in n- and p-type GaAs suggest that interstitial point defects have a strong effect on the group III diffusion.

Fermi-Level Effect on Group III Atom Interdiffusion in III-V Compounds: Bandgap Heterogeneity and Low Silicon-Doping

1997 ◽  
Vol 490 ◽  
Author(s):  
C.-H. Chen ◽  
U. Gösele ◽  
T. Y. Tan
Keyword(s):  
Fermi Level ◽  
Equilibrium Concentration ◽  
Electric Field Effect ◽  
Silicon Doping ◽  
Group Iii ◽  
Semiconductor Superlattice ◽  
Effect Model ◽  
N Doping ◽  
Short Annealing ◽  
Level Effect

ABSTRACTHeavy n-doping enhanced disordering of GaAs based III-V semiconductor superlattice or quantum well layers, as well as the diffusion of Si in GaAs have been previously explained by the Fermi-level effect model with the triply-negatively-charged group III lattice vacancies identified to be the responsible point defect species. These vacancies have a thermal equilibrium concentration proportional to the cubic power of the electron concentration n, leading to the same dependence of the layer disordering rate. In this paper, in addition, we take into account also the electric field effect produced by the material bandgap heterogeneity and/or hetero-junctions. In heavily n-doped or long time annealing cases, this effect is negligible. At low n-doping levels and for short annealing times, the layer disordering rate can be enhanced or reduced by this effect. Available experimental results of low Si-doped and very short-time annealed samples have been satisfactorily fitted using the Fermi-level effect model.

Diffusion of Gold into Heavily Boron-Doped Silicon

1997 ◽  
Vol 469 ◽  
Author(s):  
H. Bracht ◽  
A. Rodriguez Schachtrup
Keyword(s):  
Doping Level ◽  
Hole Concentration ◽  
Effective Diffusion ◽  
Boron Doped ◽  
Enthalpy Difference ◽  
Background Doping ◽  
B Doping ◽  
P Type ◽  
Level Effect ◽  
Positively Charged

ABSTRACTDiffusion of Au into dislocation-free and highly dislocated Si with high B-background doping levels has been investigated with the aid of neutron activation analysis in conjunction with mechanical sectioning. The high B-doping level causes extrinsic conditions, i.e., the hole concentration exceeds the intrinsic carrier concentration even at diffusion temperatures between 900°C and 1100°C. All profiles are accurately described on the basis of the kick-out diffusion model and a mechanism which takes into account segregation of Au at dislocations. Our analysis provides solubility data of Au in Si and effective diffusion coefficients related to interstitial Au and Si self-interstitials I. The dependence of these quantities on the B-background doping level is well described by the Fermi-level effect. This analysis supports singly positively charged states in p-type Si of Au on interstitial (Aui) and substitutional (Aus) sites and of Si self-interstitials. Successful fitting of additionally requires an acceptor level of Aus. The electrical properties deduced for Aui, Aus and I are summarized in Table 2. Au profiles in highly dislocated Si obtained especially after diffusion at 900° C give evidence of Au trapped at dislocations. From our preliminary experimental results we determine an enthalpy difference of 2.7 eV between Au on substitutional sites and Au captured at dislocations.

Are the Models of the Triply Charged Gallium Vacancy and Doubly Charged Gallium Interstitial Alive or Dead?

1995 ◽  
Vol 378 ◽  
Author(s):  
R. M. Cohen ◽  
C. Y. Chen ◽  
W. M. Li ◽  
D. S. Simons ◽  
P. H. Chi
Keyword(s):  
Negative Charge ◽  
Growth Conditions ◽  
Gallium Vacancy ◽  
Group Iii ◽  
Multiply Charged ◽  
Diffusion Mechanisms ◽  
P Type ◽  
Doubly Charged ◽  
Charged Defects ◽  
Positively Charged

AbstractWe have found that the measured diffusivity can be quite different than predicted by recent models of multiply-charged defects. Key problems dealing with the measurement and the interpretation of diffusion mechanisms are discussed. Using a few common variations in GaAs epilayer growth, we have obtained diffusivities which range over several orders of magnitude at the same temperature. Making use of the relatively weak In-As bond, we have used In as a marker to measure group III interdiffusion, DIII. DIII is consistent with the results of others using Al as a marker in n-type GaAs, but orders of magnitude smaller than predicted by the triply charged Ga vacancy, V3−Ga, model of Tan and Gosele. Although diffusion can be attributed to a negatively charged vacancy in n-type GaAs, In is found to often move by a kick-out mechanism in p-type GaAs. It appears likely that many early experiments with n- and p-type GaAs-AlAs interdiffusion were affected by large concentrations of Ga interstitials, IGa, caused by Fermi energy pinning at the growing surface. We present the first direct experimental evidence for the existence of a positively charged Ga interstitial. Our results, combined with those of others, suggest that VGa has a single negative charge associated with it. Because epilayer growth conditions appear to cause the point defect concentrations to deviate substantially from equilibrium, we conclude that the exact charge states of VGa and IGa still remain to be determined.

First-Principles Study on the Conductive Properties of P-Doped ZnO

2009 ◽  
Vol 79-82 ◽  
pp. 1253-1256 ◽  
Author(s):  
Li Guan ◽  
Qiang Li ◽  
Xu Li ◽  
Jian Xin Guo ◽  
Bo Geng ◽  
...  
Keyword(s):  
Fermi Level ◽  
Valence Band ◽  
Density Functional ◽  
Lattice Structure ◽  
Mulliken Charge ◽  
Total Density ◽  
Type Conductivity ◽  
Doped Zno ◽  
P Type ◽  
Conductive Properties

In the present paper, the lattice structure, band structure and density of state of pure and P-doped ZnO are calculated by first-principle method based on density functional theory. By analyzing the Mulliken charge overlap population and bond length, it is found that the bond of P-Zn is longer and stronger than O-Zn bond for PO-ZnO. But for PZn-ZnO, the O-P bond becomes shorter and more powerful than O-Zn bond. Also, weak O-O bonds are formed in this case. Our results show that the final total energy of PO-ZnO is lower than PZn-ZnO. The lattice structure of PO-ZnO is more stability than PZn-ZnO. For PO-ZnO, The Fermi level moves into the valence band, which expresses that the holes appear on the top of valence band and thus the PO-ZnO exhibits p-type conductivity. For PZn-ZnO, the Fermi level moves up to the conductor band and the total density of states shifts to the lower energy region, thus PZn-ZnO shows the n-type conductivity.

An effective and efficient approach to p-type AlN by Be2:O codoping from first-principles calculations

2016 ◽  
Vol 30 (20) ◽  
pp. 1650257
Author(s):  
Meng Zhao ◽  
Wenjun Wang ◽  
Jun Wang ◽  
Junwei Yang ◽  
Weijie Hu ◽  
...  
Keyword(s):  
First Principles ◽  
Ionization Energy ◽  
Hole Concentration ◽  
Valence Band Maximum ◽  
First Principles Calculations ◽  
Mutual Compensation ◽  
Efficient Approach ◽  
P Type ◽  
Codoping Method

Various Be:O-codoped AlN crystals have been investigated via first-principles calculations to evaluate the role of the different combinations in effectively and efficiently inducing p-type carriers. It is found that the O atom is favored to bond with two Be atoms. The formed Be2:O complexes decrease the acceptor ionization energy to 0.11 eV, which is 0.16 eV lower than that of an isolated Be in AlN, implying that the hole concentration could probably be increased by 2–3 orders of magnitude. The electronic structure of Be2:O-codoped AlN shows that the lower ionization energy can be attributed to the interaction between Be and O. The Be–O complexes, despite failing to induce p-type carriers for the mutual compensation of Be and O, introduce new occupied states on the valence-band maximum (VBM) and hence the energy needed for the transition of electrons to the acceptor level is reduced. Thus, the Be2:O codoping method is expected to be an effective and efficient approach to realizing p-type AlN.

Dislocation scatterings in p-type Si1−xGexunder weak electric field

2015 ◽  
Vol 26 (49) ◽  
pp. 495201 ◽  
Author(s):  
Ji-Hyun Hur ◽  
Sanghun Jeon
Keyword(s):  
Electric Field ◽  
Weak Electric Field ◽  
P Type

Interaction of Point Defects with Impurities in the Si-SiO2 System and its Influence on the Properties of the Interface

2009 ◽  
Vol 156-158 ◽  
pp. 145-148 ◽  
Author(s):  
Daniel Kropman ◽  
E. Mellikov ◽  
K. Lott ◽  
Tiit Kärner ◽  
Ivo Heinmaa ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Magnetic Resonance ◽  
Fermi Level ◽  
Point Defects ◽  
Interface Properties ◽  
Hydrogen Ions ◽  
Paramagnetic Resonance ◽  
Proposed Model ◽  
P Type ◽  
Electron Paramagnetic

The results of investigation of the point defect generation and interaction with impurities in the Si-SiO2 system during the process of its formation by means of electron paramagnetic resonance (EPR) and nucleous magnetic resonance (NMR) technique are presented. It has been shown that the diference in point defects interaction with hydrogen at the Si-SO2 interface with n- and p-type conductivity are connected with the sign of hydrogen ions incorporation dependence on the Fermi level position in accordance with the proposed model. The interface properties may be improved by laser irradiation.

High hole concentration of p-type InGaN epitaxial layers grown by MOCVD

2006 ◽  
Vol 498 (1-2) ◽  
pp. 113-117 ◽  
Author(s):  
Po-Chang Chen ◽  
Chin-Hsiang Chen ◽  
Shoou-Jinn Chang ◽  
Yan-Kuin Su ◽  
Ping-Chuan Chang ◽  
...  
Keyword(s):  
Hole Concentration ◽  
Epitaxial Layers ◽  
High Hole Concentration ◽  
P Type
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