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1

Influence of surface states and bulk traps on non-equilibrium phenomena at GaAs and GaN surfaces

Miczek M., Adamowicz B., Hashizume T., Hasegawa H.

Optica Applicata

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2005

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Vol. 35, nr 3

355-361

EN

The influence of surface state density Nss and bulk non-radiative lifetime t(tau) on room temperature photoluminescence quantum efficiency YPL and surface photovoltage (SPV) versus the excitation light intensity F(fi) was studied theoretically for GaAs and wurtzite GaN using self-consistent computer simulations. It was demonstrated that SPV(F) dependences are more sensitive than YPL (F) to a change in magnitude of Nss, especially for high Nss and at low F, whereas SPV is practically insensitive to t contrary to YPL. The simultaneous measurement of YPL and SPV versus , combined with rigorous computer analysis, seems to be a very promising method for contactless characterization of the surface and bulk trap parameters.

2

Characterization of electronic properties of InP(100) surfaces from computer-aided analysis of photoluminescence

Miczek M., Adamowicz B., Hasegawa H.

Optica Applicata

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2002

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Vol. 32, nr 3

226-233

EN

The surface state density distributions NSS(E) on the InP surface were determined by employing a rigorous computer analysis of the dependences of the band-to-band photoluminescence efficiency YPL versus excitation light intensity F. Experimental YPL–F spectra, taken from the literature, were obtained for the n-InP (100) surface after chemical polishing and ion bombardment. Theoretical Y PL–F curves were calculated using a numerical simulator which takes into account all bulk and surface recombination processes. The NSS(E) distributions were determined for both surfaces from the best fit to experimental data by applying a procedure based on genetic algorithm. An increase in NSS(E) after ion bombardment was attributed to the surface disordering. The behaviour of the effective surface recombination velocity and quasi-Fermi levels for electrons and for holes versus F was also analysed.

3

Determination of the surface state density distribution and fermi level position on the InP (100) surface from excitation-power-dependent photoluminescence efficiency spectra

Adamowicz B., Miczek M., Domagała T., Hasegawa H.

Elektronika : konstrukcje, technologie, zastosowania

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2001

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Vol. 42, nr 8-9

76-78

EN

The energy distribution of the surface state density NSS(E) on the chemically polished n-type InP (100) surface was determined from a rigorous computer analysis of the band-to-band photoluminescence efficiency (ϒ PL) versus excitation light intensity (θ). We obtained a very good modelling of the experimental ϒ PL-θ spectrum, taken from the literature, which exhibited a strong increase of ϒ PL. The theoretical values of ϒ PL were calculated using a numerical simulator taking account of all possible recombination processes in a bulk and via surface states. Due to an optimised fitting realised by means of a novel fully-computer procedure based on Genetic Algorithm, we determined the U-shaped NSS(E) distribution as well as the values of surface state cross sections for capturing electrons (σn) and holes (σp). In addition, we analysed the behaviour of the quasi-Fermi levels (EFn, EFp) on the surface and profiles of the radiative recombination velocity (Urad) under increasing excitation intensity.