Influence of Growth Parameters on a‐Plane InGaN/GaN Heterostructures on r‐Sapphire

Abstract

The n‐type and p‐type a‐GaN films are successfully grown by MOCVD on the r‐sapphire substrate with smooth mirror surface morphology. The growth rate versus the growth temperature is investigated. Optimum doping parameters by acceptor and donor impurities − 8 × 1017 and 4 × 1018 cm−3 are determined. Low‐temperature amorphous buffer (nucleus) GaN layer and the island growth process with additional doping profile in quantum wells (QW) are investigated. The heterostructures are grown based on direct investigation and simulation results and are investigated by atomic‐force microscopy (AFM) and scanning electron microscopy (SEM). In this work, V‐defects of the structure for non‐polar orientation films are investigated for the first time, thus complementing earlier results for polar and semi‐polar films. The results indicate that the defect density was reduced up to 104 cm−2, with improved surface morphology uniformity. During growth, the influence from V/III flow ratio and doping barriers by indium atoms was detected. Decrease in the V/III ratio up to 1320 at the overgrowth stage of the precipitated low‐temperature nuclei caused growth‐island formation and increased the growth rate in the lateral direction, thus decreasing the dislocation density.

Defect‐Induced Effects in Nanomaterials

“…P. Malinsky et al traced in their work the structural and compositional changes of graphene oxide induced by irradiation with 500 keV helium and gallium ions. M. Orlova et al focused their efforts on studies of the influence of growth parameters on a‐plane InGaN/GaN heterostructures on r‐sapphire. J. Gomes et al have proven that GaN HEMTs containing deep‐level traps obey the two fundamental memristive criteria and suggested a deep‐level trapping‐related variable as the most probable hidden state variable.…”