Morphology and photoluminescence studies of electrochemically etched heavily doped p-type GaAs in HF solution

Porous GaAs layers have been produced by electrochemical anodic etching of (100) heavily doped p-type GaAs substrate in HF solution. Scanning electron microscopy revealed the presence of etch pits ranging in size from 0.01 to 2 mm and they were strongly dependent on the electrochemical etching conditions. The etch pits chemical composition consists of O, Ga and As whereas the porous structure consists predominantly of GaAs as performed by energy dispersive X-ray analyzer. Typical porous structure with pores diameter ranging from 15 to 50 nm has been obtained. Room temperature photoluminescence (PL) investigations reveal the presence of two and in one case three PL bands besides the PL band of the started GaAs. Peaks wavelengths positions were approximately located in 600–900 nm range. The PL bands peaks wavelengths positions depend on the electrochemical etching conditions and they were approximately unchanged with increasing temperature. However, their PL intensity increased slowly with increasing temperature and tend to saturate. The observed PL bands were explained by the quantum confinement effects in GaAs nanocrystallites. q 2003 Elsevier Ltd. All rights reserved. PACS: 78.20.e; 78.30.Hv; 78.55.Cr; 81.60.Cp