Ultra shallow sidewall GaAs tunnel junctions prepared by low-temperature area-selective epitaxial re-growth method

Abstract

Low-temperature (290 °C) area-selective re-growth (LT-ASR) by molecular layer epitaxy (MLE) was applied to the fabrication of ultra shallow (50 nm) sidewall GaAs tunnel junctions. As a result, these tunnel junctions have exhibited record peak current densities of up to 31,000 A/cm 2 at RT, with a peak-to-valley current ratio of 2.1. It was also shown that the tunnel junction characteristics are strongly dependent on the sidewall mesa orientation. In order to investigate the midgap levels at the re-growth interface region, photocapacitance (PC) measurements were made on area-selective re-grown sidewall p + i n + junctions.