THERMAL-STABILITY OF STRAINED INXGA1-XAS INYAL1-YAS/INP HETEROSTRUCTURES/

We investigated the thermal stability of strained layers of InGaAs and InAlAs on InP. Epilayer and interface quality was assessed by high-re solution x-ray diffraction and electron mobility measurements as a fun ction of annealing cycle. Both techniques show that pseudomorphic hete rostructures retain their high crystalline quality at annealing temper atures of up to 700-800-degrees-C, despite exceeding the Matthews-Blak eslee [J. Cryst. Growth 27, 118 (1974)] critical layer thickness by as much as a factor of 4-8. On the other hand, layers which are partiall y relaxed (incoherent) as-grown relax further during annealing. These findings demonstrate that layers which are beyond the predicted critic al thickness, but coherently strained after growth, are stable to norm al device processing and operating temperatures and hence may be suita ble for use in device heterostructures.