Electrical and Structural Properties of W-Capped Er Ohmic Contact to n-Type in0.53Ga0.47As Channel

We have investigated electrical and microstructural properties of W-capped Er Ohmic contact to n-type In_0.53Ga_0.47As channel using (I-V) current-voltage characteristics, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The interfacial reaction between Er and In_0.53Ga_0.47As driven by rapid thermal annealing (RTA) process led to the formation of Er-InGaAs alloy. The increase in the RTA temperature resulted in the degradation of surface and interface morphologies of Er-InGaAs alloy film, which could be associated with the reduction of its surface energy combined with intense interfacial reaction between Er and In_0.53Ga_0.47As. The specific contact resistivity of Er-InGaAs alloy film extracted using four-point (Kelvin) probe technique was investigated as a function of RTA temperature. The specific contact resistivity was found to vary with the variation in RTA temperature. Such a dependency of specific contact resistivity on RTA temperature could be attributed to the phase evolution surface/interface morphologies of Er-InGaAs alloy film. A minimum specific contact resistivity of ~ 10^-6 Ωcm² was achieved after RTA process at 400 °C.