Abstract
Porous GaAs layers have been formed by electrochemical anodic etching of (1 0 0) heavily doped p-type GaAs substrate in a HF:C2H5-OH solution. The surface morphology of porous GaAs has been studied using atomic force microscopy (AFM).
Nano-structural nature of the porous layer has been demonstrated by X-ray diffraction analysis (XRD) and confirmed by AFM. An estimation of the main size of the GaAs crystallites obtained from effective mass theory and based on PL data was close to the lowest value obtained from the AFM results. The porous p-GaAs samples are characterised by spectroscopic ellipsometry and modulation spectroscopy techniques. The objective of this study is to determine the porosity, refractive index, and thickness. The porosity of GaAs determined by atomic force microscopy confirmed by the value obtained from the spectroscopic ellipsometry. In fact the current voltage I(V) characteristics of metal semiconductor Au/p-GaAs are investigated and compared with Au/p-porous GaAs structures. From the forward bias I(V) characteristics of these devices, the main electrical parameters such as ideality factor, barrier height, and series resistance have been determined. (C) 2013 Elsevier Ltd. All rights reserved.