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.

Simulation of Under- and Supersaturation of Gallium Vacancies in Gallium Arsenide During Silicon in- and Outdiffusion

1997 ◽  
Vol 490 ◽  
Author(s):  
C.-H. Chen ◽  
U. Gösele ◽  
T. Y. Tan
Keyword(s):  
Gallium Arsenide ◽  
Fermi Level ◽  
Point Defect ◽  
Surface States ◽  
Effect Model ◽  
N Doping ◽  
Defect Species ◽  
Concentration Of Electrons ◽  
Level Effect ◽  
Doping Condition

ABSTRACTThe diffusivity of Si in GaAs shows a dependence on the cubic power of its concentration or the concentration of electrons n under both in- and outdiffusion conditions. Hence, the diffusion of Si in GaAs is consistent with the Fermi-level effect model invoking the triply-negatively-charged Ga vacancies, , as the point defect species responsible for diffusion to occur on the Ga sublattice under n-doping condition. However, the Si diffusivity values of the indiffusion cases is several orders of magnitude smaller than those of the outdiffusion cases at the same Si concentrations. This means that the two apparent Si diffusivity values under intrinsic conditions will contain also the same discrepancy, which has been previously assessed to be due to a undersaturation in indiffusion cases and a supersaturation in outdiffusion cases. In this study we have calculated the under- and supersaturation values using the known Si diffusivities. We found that the GaAs surface states play a key role in the development of the under- and supersaturations.

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.

Fermi-Level Effect, Electric Field Effect, and Diffusion Mechanisms in GaAs Based III-V Compound Semiconductors

1998 ◽  
Vol 527 ◽  
Author(s):  
T. Y. Tan ◽  
C.-H. Chen ◽  
U. Gösele ◽  
R. Scholz
Keyword(s):  
Electric Field ◽  
Fermi Level ◽  
Point Defects ◽  
Field Effect ◽  
Pressure Effect ◽  
Electric Field Effect ◽  
Diffusion Mechanisms ◽  
And Diffusion ◽  
Level Effect

ABSTRACTDiffusion mechanisms and point defects in GaAs and related III-V compounds are discussed. An understanding of the As sublattice situation has been arrived at fairly recently and is presently tentative. Understanding of the Ga sublattice situation has become more acceptable in that experimental results are consistently explained by the Fermi-level effect and the As4 pressure effect. On the Ga sublattice, though controversies still exist, some are readily resolved by noting the role of the electric field produced by semiconductor electrical junctions, physical junctions, and surfaces.

Mechanisms of Doping-Enhanced Superlattice Disordering and of Gallium Self-Diffusion in GaAs

1987 ◽  
Vol 104 ◽  
Author(s):  
T. Y. Tan ◽  
U. Gösele ◽  
B. P. R. Marioton
Keyword(s):  
Fermi Level ◽  
Point Defect ◽  
Dopant Diffusion ◽  
Self Diffusion ◽  
N Doping ◽  
Charged Point Defect ◽  
Charged Point ◽  
Defect Species ◽  
Level Effect ◽  
Positively Charged

ABSTRACTRecently available Ga-Al interdiffusion results in GaAs/AlAs superlattices allow to conclude that Ga self-diffusion in GaAs is carried by triply-negatively charged Ga vacancies under intrinsic and n-doping conditions. The mechanism of the Si enhanced superlattice disordering is the Fermi-level effect which increases the concentrations of the charged point defect species. For the effect of the p-dopants Be and Zn, the Fermi-level effect has to be considered together with dopant diffusion induced Ga self-interstitial supersaturation or undersaturation. Self-diffusion of Ga in GaAs under heavy p-doping conditions is governed by positively charged Ga self-interstitials.

Layer Disordering and Carrier Concentration in Heavily Carbon-Doped AlGaAs/GaAs Superlattices

1993 ◽  
Vol 300 ◽  
Author(s):  
H. M. You ◽  
T. Y. Tan ◽  
U. M. Gösele ◽  
G. E. Höfler ◽  
K. C. Hsieh ◽  
...  
Keyword(s):  
Fermi Level ◽  
Carrier Concentration ◽  
Hole Concentration ◽  
Concentration Profiles ◽  
Precipitation Mechanism ◽  
Carbon Doped ◽  
Effect Model ◽  
The One ◽  
Level Effect

ABSTRACTAl-Ga interdiffusion, carbon acceptor diffusion, and hole reduction were studied in carbondoped Al0.4Ga0.6As/GaAs superlattices (SL). Al-Ga interdiffusion was found to be most prominent for Ga-rich annealing, with the hole concentrations in the SL almost intact during annealing. For As-rich annealing, the interdiffusivity values, DAI.Ga, are in approximate agreement with those predicted by the Fermi-level effect model, and the hole concentrations in the SL decreased dramatically after annealing. By analyzing the measured hole concentration profiles, it was found that both carbon acceptor diffusion and reduction have occurred during annealing, with both depending on As4 pressure values to the one quarter power. These As4 pressure dependencies indicate that carbon diffuses via the interstitial-substitutional mechanism while hole reduction is governed by a precipitation mechanism.

On Surface Cracking of Ammonia for MBE Growth of GaN

1996 ◽  
Vol 449 ◽  
Author(s):  
M. Kamp ◽  
M. Mayer ◽  
A. Pelzmann ◽  
K. J. Ebeling
Keyword(s):  
Material Properties ◽  
Group Iii Nitrides ◽  
Growth Mechanisms ◽  
Mbe Growth ◽  
Group Iii ◽  
Surface Cracking ◽  
Homoepitaxial Growth ◽  
N Doping

ABSTRACTWith the use of ammonia as nitrogen precursor for Group III-Nitrides in an on surface cracking (OSC) approach, MBE becomes a serious competitor to MOVPE. Homoepitaxial GaN exhibits record linewidths of 0.5 meV in PL (4K), whereas GaN grown on c-plane sapphire also reveals reasonable material properties (PL linewidth ≈ 5 meV, n ≈ 1017 cm-3 , μ 220 cm2/Vs). Beside results on hetero- and homoepitaxial growth of GaN, insights into the growth mechanisms are presented. The growth of ternary nitrides is discussed, p- and n-doping as well as first LED results are reported.

Fundamentals, Material Properties and Device Performances in GaN MBE using On-Surface Cracking of Ammonia

1997 ◽  
Vol 2 ◽  
Author(s):  
Markus Kamp ◽  
M. Mayer ◽  
A. Pelzmann ◽  
K. J. Ebeling
Keyword(s):  
Molecular Beam Epitaxy ◽  
Material Properties ◽  
Molecular Beam ◽  
Group Iii Nitrides ◽  
Group Iii ◽  
Surface Cracking ◽  
Organic Vapor ◽  
N Doping ◽  
Metal Organic ◽  
Uv Leds

Ammonia is investigated as nitrogen precursor for molecular beam epitaxy of group III nitrides. With the particular on-surface cracking approach, NH3 is dissociated directly on the growing surface. By this technique, molecular beam epitaxy becomes a serious competitor to metal organic vapor phase epitaxy. Thermodynamic calculations as well as experimental results reveal insights into the growth mechanisms and its differences to the conventional plasma approach. With this knowledge, homoepitaxially GaN can be grown with record linewidths of 0.5 meV in photoluminescence (4 K). GaN layers on c-plane sapphire also reveal reasonable material properties (photoluminescence linewidth 5 meV, n ≈ 1017 cm−3, μ ≈ 220 cm2/Vs). Beside GaN growth, p- and n-doping of GaN as well as the growth of ternary nitrides are discussed. Using the presented ammonia approach UV-LEDs emitting at 370 nm with linewidths as narrow as 12 nm have been achieved.

An Examination of the Mechanisms of Si Diffusion in GaAs

1989 ◽  
Vol 163 ◽  
Author(s):  
Shaofeng Yu ◽  
Ulrich M. Gosele ◽  
Teh Y. Tan
Keyword(s):  
Fermi Level ◽  
Point Defect ◽  
Essential Role ◽  
Defect Concentration ◽  
Experimental Results ◽  
Quantitative Models ◽  
Effect Mechanism ◽  
Level Effect

AbstractAn examination of the three available quantitative models of Si diffusion in GaAs has led to the conclusion that the Fermi-level effect mechanism plays the most essential role. In some experimental results a point defect concentration transient is involved which should be incoorporated in future models.

Sign in / Sign up

Export Citation Format

Share Document