Electrical and structural properties of GaN films and GaN/InGaN light-emitting diodes grown on porous GaN templates fabricated by combined electrochemical and photoelectrochemical etching

Abstract

Porous GaN templates were prepared by combined electrochemical etching (ECE) and back-side photoelectrochemical etching (PECE), followed by the overgrowth of GaN films and InGaN/GaN multiple quantum well (MQW) light-emitting diode (LED) structures. Structural, luminescent, and electrical properties of the GaN and LED structures were studied and compared with the properties of structures grown under the same conditions on templates not subjected to ECE–PECE treatment. Overgrowth of LED structures on the ECE–PECE templates reduced strain, cracking, and micropits, leading to increased internal quantum efficiency and light extraction efficiency. This luminescence enhancement was observed in overgrown GaN films, but was more pronounced for InGaN/GaN LED structures due to suppression of piezoelectric polarization field in QWs.