Determination of the absorption coefficient and the internal luminescence spectrum of GaAs and GaAs1−xPx (x = 0.375, 0.78) from beam voltage dependent measurements of cathodoluminescence spectra in the scanning electron microscope

Abstract

On GaAs and GaAs1–xPx (x = 0.375, 0.78) samples the beam voltage dependence of the CL spectra and the EBIC signal are measured. From the analysis of the experimental data by fitting the theoretical voltage dependent CL signal using minority carrier diffusion length values derived from the EBIC measurements the optical absorption coefficient and the internal spectral distribution of the recombination radiation in the relevant wavelength region are obtained. The results for various semiconductor materials clearly demonstrate differences in the shape of the optical absorption edge in the wavelength regions investigated which correspond to observed shifts between the internal and the external spectral distribution of the recombination radiation.

Cathodoluminescence Calculation of n-GaAs. Surface Analysis and Comparison

“…The attenuation of photons propagating towards the surface is given by an exponential law. Hence, the CL intensity is given by where a b is the absorption coefficient of the material, which depends on the wavelength l [2]. In the past, theoretical methods to simulate CL signals have been proposed [6][7][8].…”

“…Hergert et al [6] studied CL emission using the theoretical expression for a CL signal derived in Refs. [2,15], a generation function given by Wu and Wittry [4], and the material parameters, particularly reduced surface recombination velocity (S), diffusion length (L), optical absorption coefficient (a), and dead-layer thickness (Z T ).…”

“…dislocations, precipitates, stacking faults, micro-defects, grain boundaries) [1]. The CL and EBIC techniques offer the possibility of determining reliable quantitative information on local electronic and optical material parameters, such as diffusion length and absorption coefficient [2], and recombination behaviour at defects such as dislocations and free surfaces [3]. The quantitative determination of material parameters requires an accurate simulation of the CL signal as a function of electron beam parameters (i.e.…”

Microscale characterisation of epitaxial semiconducting homolayers. - II. Electron beam induced current

“…François Cleton(1), Brigitte Sieber (1) and Jean Luc Loffiaux (2) (1) Laboratoire [1][2][3][4][5][6][7][8][9][10], and a local determination of the doping level is possible by EBIC [8][9][10]. In the case of multilayer structures, interface recombination velocities can also be determined [1,11].…”

Microscale characterisation of epitaxial semiconducting homolayers. - I. Cathodoluminescence

“…Numerous reliable EBIC models are available for measuring the diffusion length in bulk specimens, whatever is the junction position with respect to the surface bombarded by the incident electron beam (see for instance [1]). The number of papers dealing with the determination of L in bulk specimens by CL experiments is more limited [2][3][4]; as a matter of fact, the recent developement of CL comes from the increased interest in optoelectronics semiconductors such as III-V and II-VI compounds. It has the advantage, over EBIC, not to require the preparation of an electrical barrier.…”