Effect of rapid thermal annealing on the optical and electrical properties of metamorphic high electron mobility transistor structures with composite InGaAs∕InP channel

Abstract

The electrical and optical properties of metamorphic InGaAs∕InP composite channel high electron mobility transistor (HEMT) structures subjected to rapid thermal annealing (RTA) are systematically investigated in the temperature range of 350–650°C. The metamorphic structures exhibit different degradation behaviors in different temperature ranges as compared to lattice-matched (control) structure. For the samples annealed at temperature lower than 550°C, increase in annealing temperature results in a larger degradation of sheet carrier density (ns) and photoluminescence (PL) intensity. However, no further reduction of ns was observed in the metamorphic samples after RTA at temperature higher than 550°C. An improvement of PL intensity in the temperature range of 550–650°C for metamorphic samples was even observed. This behavior is absent in the lattice-matched HEMT structures. Possible mechanisms governing the change of the electrical and optical properties in metamorphice HEMT structures are discussed. Our experimental results reveal that, compared to the lattice-matched structures, the InP HEMT structures grown on GaAs using metamorphic structure could present similar thermal stability up to 650°C even though a metamorphic strain-relief buffer is included. This may partially ease the concerns on the thermal stability of the metamorphic HEMT structures.