Control and elimination of cracking of AlGaN using low-temperature AlGaN interlayers

Abstract

We demonstrate that the insertion of low-temperature (LT) AIGaN interlayers is effective in reducing mismatch-induced tensile stress and suppressing the formation of cracks during growth of AIGaN dkectly upon GaN epilayers., Stress evolution and relaxation is monitored using an in-situ optical stress sensor.

Growth of High Quality Al x Ga 1—x N with High Al‐Composition for Schottky‐Type UV Detector Using MOCVD

“…Among them, Al x Ga 1--x N/LT-Al x Ga 1--x N interlayer/n + -GaN/LT-GaN buffer (type III) was evaluated as the most competitive structure due to its higher moblity of 290 cm 2 /Vs, lower leakage current of 9 nA, and much simpler growth procedure. Furthermore, the type III Pt/Al 0.33 Ga 0.67 N UV detector exhibited an outstanding UV to visible extinction ratio of~10 4 and photo-responsivity of 0.15 A/W at 280 nm. …”

“…Recently, Amano et al [3] reported on the growth of crack-free thick Al x Ga 1--x N films by introducing a thin AIN interlayer, grown at a low temperature, between the GaN and Al x Ga 1--x N layer. Han et al [4] also reported on controlling the cracking of Al x Ga 1--x N based on a low-temperature Al x Ga 1--x N interlayer. In this work, we proposed and investigated three layer structures of thick Al x Ga 1--x N films with a high Al mole fraction for application of Schottky-type UV photodetectors.…”

On the effect of N-GaN/P-GaN/N-GaN/P-GaN/N-GaN built-in junctions in the n-GaN layer for InGaN/GaN light-emitting diodes

“…A p-type AlGaN electron blocking layer (EBL) is used to block electrons from escaping to the p-GaN region [7]. Moreover, an n-type AlGaN layer inserted below the active region for the reduction of the electron overflow has also been proposed [8][9][10]. (3) Current crowding effect for InGaN/GaN LEDs grown on insulating sapphire substrates with lateral current injection scheme causes non-uniform light emission across the device area and reduces the quantum efficiency [11,12].…”

Valence band offsets of ScxGa1−xN/AlN and ScxGa1−xN/GaN heterojunctions

“…The low efficiencies are due in part to the extended defects which appear within the active light-emitting regions of device heterostructures due to the lattice constant mismatch between layers. The high tensile stresses which typically develop due to the lattice constant and thermal expansion coefficient mismatches between layers within a UV-LED device structure also limit the total device thickness and the variety of structures which can be grown successfully [10][11][12] . Therefore, alternative wurtzite nitrides such as Sc x Ga 1-x N with different lattice parameter -band gap relationships 13 are of interest to control internal stresses and open up new routes to device design.…”