Comparative characteristics of plasma etched GaAs and InP

Abstract

Plasma etching was performed on GaAs and InP to prepare the surface before Schottky metal deposition. A comparative study was carried out for the two materials to study the influence of CF4 plasma etching on material properties and device characteristics. Photoreflectance (PR) and electroreflectance (ER) spectroscopy measurements were conducted to study the effect of plasma etching on the material surface. The PR and ER spectra showed the introduction of considerable radiation damage by dry etching. Current–voltage (I–V) and deep level transient spectroscopy (DLTS) were used for device characterization and defect level identification. Rapid thermal annealing (RTA) effectively removed the damage which was evident by all test techniques. The Schottky diodes on the GaAs control wafer, the plasma etched wafer, and the wafer after RTA showed barrier heights φB of 0.82, 0.65, and 0.86 eV, respectively. For InP, the plasma etched sample showed such serious damage that no Schottky contact was achieved. For the control wafer and the plasma etched wafer after RTA, the barrier heights obtained were 0.50 and 0.49 eV. The DLTS results showed two trap levels in GaAs with activation energy below the conduction band of 0.634 and 0.397 eV introduced by plasma etching. For both GaAs and InP, the control wafer and plasma etched sample after RTA showed very similar DLTS spectra which indicated the effectiveness of the RTA treatment.