Optical Properties of GaAs Porous Layers Fabricated on Wafers Pre-Irradiated with Gamma Radiation

In this paper, we an investigation of the characteristics of porous gallium arsenide layers fabricated GaAs substrates subjected to low-dose gamma irradiation. We selected gamma radiation doses during the processing of gallium arsenide wafers in the range of 10 to 200 kR. Porous GaAs layers are obtained by electrochemical etching in galvanostatic mode. Changes in the surface morphology of the studied porous GaAs layers obtained on irradiated substrates are presented. In the Raman spectra, phonon bands of LO and TO modes are observed in the frequency range of 145 cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> and 150 cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup>. The TO/LO ratio increases with increasing wafer irradiation dose. Porous GaAs samples exhibit phonon peaks of other compounds Ga<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>, As<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>, and amorphous GaAs. The change in the intensity of the Raman spectrum peaks is determined by the irradiation dose of the wafers. With increasing irradiation dose to wafers, the intensity of the maximum photoluminescence peak for porous layers decreases. From the spectral dependences of photoluminescence, a change in the size of GaAs nanocrystallites was obtained with increasing irradiation dose from 14.5 to 10 nm (860 nm region) and about 3–4 nm (for the 630 nm region).