MBE-growth and characterization of In$_{x}$Ga$_{1-x}$As/GaAs (x=0.15) superlattice

Abstract

A qualified In$_{0.15}$Ga$_{0.85}$As/GaAs superlattice was grown on an n-type GaAs(100) substrate by molecular beam epitaxy(MBE). Analysis of this structure was first carried out by X-Ray diffraction(XRD) and this structure's the interface thicknesses, roughness and x concentration determined at nanoscale. Secondly, the electrical characteristics of this sample such as the current-voltage-temperature (I-V-T), capacitance-voltage-temperature (C-V-T) and conductance-voltage temperature (G-V-T) were studied over a wide temperature range. The energy distribution of interface states was determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height. Experimental results show that the forward and reverse I-V characteristics are similar to Schottky-junction behavior. The ideality factor n, series resistance $R_{s}$, barrier height $\Phi_{B}$ and density of interface states $N_{ss}$ were found to be strong functions of temperature. According to thermionic emission (TE) theory, the zero-bias barrier height $(\phi _{Bo})$ calculated from forward bias I-V characteristics was found to increases with increasing temperature. In addition, the value of $R_{s}$ as a function of both voltage and temperature was obtained from C-V and G-V characteristics. The temperature dependent of I-V, C-V and G-V characteristics confirmed that the distribution the $R_{s}$ and $N_{ss}$ are important parameters that influence the electrical characteristics of these devices.