Flip-chip blue LEDs grown on bulk GaN substrates utilizing photoelectrochemical etching for substrate removal

Abstract

We demonstrate a 440 nm emitting flip-chip GaN LED utilizing photoelectrochemical (PEC) etching for substrate removal. The device was flip-chip-bonded to a thermally conductive silicon carbide substrate, which allowed for CW operation at current densities up to 200 A/cm2 with minimal thermal droop. The PEC etch provided a damage-free method of removing substrates and could allow for substrate reuse. The epitaxially defined etch also exposed a highly doped n-contact layer, which contributed to the low operating voltage of 3.74 V at 400 A/cm2 and a peak wall plug efficiency (WPE) of 7%.