The growth of resonant tunneling hot electron transistors using chemical beam epitaxy

Abstract

A systematic growth study of InGaAs/AlAs/InGaAsP resonant tunneling hot electron transistors (RHETs) was performed using chemical beam epitaxy (CBE). The resonant tunneling hot electron transistors studied consist of a highly strained AlAs/In0.75Ga0.25As/AlAs double barrier structure and an undoped InP collector barrier with 1.1 and 1.2 [mu]m InGaAsP graded layers. These quaternaries were lattice matched to InP within 2.6 x 10-4 and showed an averaged full width at half-maximum (FWHM) of 6 meV from low temperature photoluminescence (PL) measurement. The effects of growth interrupt were studied using PL, X-ray diffraction and secondary ion mass spectrometry (SIMS) measurements. It was found that excessive growth interrupt induced high oxygen accumulation (8 x 1018 cm-3) at the heterojunction and reduced the intensity of PL spectra. Moreover, for the growth of tunneling heterostructures, low substrate temperature, appropriate growth interrupts and use of hydride drying filters and high purity hydrides were helpful to improve device performance. The highest peak-to-valley current ratio (PVR) observed was 12.7, and maximum base transport ratio was 0.98 at 80 K. Furthermore, some digital functions such as flip-flop gate and exclusive NOR were demonstrated using a single RHET.