Passivation of InGaAs/InP heterostructures

Abstract

ABSTRACTIn this study we report different surface treatments and device designs that can be used to improve the performance of InGaAs/InP heterostructure devices. The surface properties of InGaAs (100) after sulfur or UV-ozone passivation were investigated by photoluminescence and high energy-resolution X-ray photoelectron spectroscopy. The base leakage current and the dc current gain of InGaAs/InP heterostructure bipolar transistors (HBTs) have been used to evaluate the efficiency of the passivation treatments. Although these treatments successfully passivated large area HBTs, the improved device characteristics degraded after a dielectric was deposited by plasma enhanced chemical vapor deposition (PECVD) or even just with time. Nevertheless, we found a combined surface treatment that is successful even under PECVD deposition – a UV-ozone treatment that produces a sacrificial oxide that is then removed by HF. This approach will be contrasted with a different method based on an optimized HBT layer structure with a thin InP emitter. In this case, the thin layer of depleted InP from the emitter left on the extrinsic base passivates the surface, and no treatment is required.