The Shape Parameter of Donor Band Tails in Gallium Arsenide

Wittmann, H. R.

doi:10.1002/pssb.19690350237

Cited by 10 publications

(4 citation statements)

References 19 publications

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“…At high temperatures W 1 : kT, indicating clearly the importance of the phonon effects.2) However, when lowering the temperature, W becomes temperature independent [513), becoming instead dependent on the impurity concentration n (in doped semiconductors). According to [9], W r~ n o 3 in this case.…”

Section: U'mentioning

confidence: 87%

Interband optical transitions in disordered semiconductors

Бонч-Бруевич¹

1970

Physica Status Solidi (b)

112

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The interband absorption coefficient is calculated for the frequency range, w, below the threshold value ("optical tail"). The tail is attributed to the influence of the random force field present in a disordered system. Two cases are considered: that of the "smooth" random field possessing a correlation function which is continuous and differentiable as many times as needed and that of the Coulomb field produced, for example, by randomly distributed charged centres. I n both cases an exponential optical tail is obtained for a sample which is in a certain sense nearly intrinsic: In a --( A -h w ) / E , where d is the band gap t h a t would have been observed without fluctuations of the force field and ZO is some characteristic energy. The tail is correlated with the density of states tail but does not reproduce it, the latter being Gaussian in the same energy range. I n the most interesting case the formation of a n optical tail is due to quantum effects in contrast to the density of states tail which may be obtained in a purely classical approximation as well. I n the Coulombic case a n explicit form of the dependence of U, on impurity concentration is obtained W -n2P. This seems t o be in agreement with the experimental data available.Der Interband-Absorptionskoeffizient wird fur den Frequenzbereich unterhalb des Schwellwertes (optischer Ausllufer) berechnet. Der Ausllufer wird dem EinfluB des ,,random-force" Feldes, das in fehlgeordneten Systemen vorhanden ist, zugeschrieben. Zwei Falle werden berucksichtigt : der eines ,,glatten" ,,Random"-Feldes mit einer Korrelationsfunktion, die kontinuierlich und beliebig oft differenzierbar ist, und der eines Coulombfeldes, das zum Beispiel durch beliebig verteilte geladene Zentren verursacht wird. I n beiden Piillen wird ein exponentieller optischer Auslaufer fur eine Probe erhalten, die in einem gewissen Sinne nahezu grundgitterahnlich ist : In a --(A --h w)/ZO, wobei A die Bandlucke, die ohne Fluktuationen des Kraftfeldes beobachtet werden wurde, und W eine charakteristische Energie ist. Der AuslLufer ist mit dem Auslaufer der Zustandsdichte verkniipft, reproduziert diesen, der in dem gleichen Energiebereich vom Gausstyp ist, jedoch nicht. I n dem a m meisten interessierenden Fall wird die Bildung eines optischen Ausllufers durch Quanteneffekte verursacht im Gegensatz zum Auslaufer der Zustandsdichte, der auch in der rein klassischen NIherung erhalten wird. Fur den Coulomb-Fall wird eine explizite Form der G-Abhlngigkeit von der Defektkonzentration n zu W N n215 erhalten. Diese scheint mit den erhiiltlichen experimentellen Werten iibereinzustimmen.

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Section: U'mentioning

confidence: 87%

Interband optical transitions in disordered semiconductors

Бонч-Бруевич¹

1970

Physica Status Solidi (b)

112

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“…Dousmanis et al [4] observed that the energy of the EL peak H. R. WITTMANN and J. L. SMITH intensity E, is related to injection current density J by J = J , exp ( E J q ) , where the constant 17 is strongly dependent on temperature and donor concentration. This observation can be explained [5] by applying the band. filling model (61 to electrons located in an exponential conduction band tail.…”

Section: Introductionmentioning

confidence: 85%

Bulk changes during catastrophic degradation of GaAs laser diodes

Wittmann

Smith

1970

Phys. Stat. Sol. (a)

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“…2 are of use here. The shape parameter 7 can be chosen by measuring the slope of hv, versus In J at low currents for various temperatures, and then using Wittmann's [4] method of extrapolating to 0 O K . The low t,emperature value of Ahv is taken from experimental data, and with the curve of Fig.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

“…Theoretical studies of the effect of doping on the band edges have been undertaken by Kane [2] and Halperin and Lax [3]. Wittmann [4] has shown that within experimental uncertainty the conduction band edge, subsequently referred to as the donor tail, can be described with an exponential or Gaussian density of states. Qualitatively, the lower region of the donor tail is the same in both cases.…”

Section: Introductionmentioning

confidence: 99%

Low-temperature electroluminescence from degenerately doped GaAs diodes

Smith

Wittmann

1970

Phys. Stat. Sol. (a)

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A model for low temperature electroluminescence from degenerately doped GaAs diodes is presented. Recombination of electrons injected into an exponential donor tail occurs with holes near the edge of the valence band in the p‐region. The effects of a decrease in the quasi‐Fermi level with distance from the p‐n junction and a hole band of finite width are incorporated in this work. The emission line shape is derived and found to be in good agreement with experimental results.

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The Shape Parameter of Donor Band Tails in Gallium Arsenide

Cited by 10 publications

References 19 publications

Interband optical transitions in disordered semiconductors

Interband optical transitions in disordered semiconductors

Bulk changes during catastrophic degradation of GaAs laser diodes

Low-temperature electroluminescence from degenerately doped GaAs diodes

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