Novel Method for Improving Process Repeatability of the AlN Buffer Layer

Abstract

A predeposition GaN process is innovatively proposed to solve the process repeatability problem of AlN buffer layer growth. First of all, it was speculated that the predeposited materials that may be present are Al, Ga, AlN, and GaN based on the introduced reaction sources. Then, the adsorption rate of each substance on the AlN surface was calculated and compared through theoretical derivation and first-principles calculation. We found that the adsorption rates of Al, Ga, AlN, and GaN on AlN surfaces are all in the same order of magnitude, indicating that Al, AlN, Ga, and GaN may coexist and affect the repeatability of the AlN film growth process together. Then, a process for suppressing impurities during AlN film growth was proposed: GaN is predeposited in the reaction chamber before the AlN film is grown, so that Al, Ga, or AlN remaining in the chamber when the AlN or AlGaN film is grown before is covered to create a single growth environment. To verify the effectiveness and reliability of this process, the reflectivity curve and crystal quality of AlN were compared. The result reveals that the GaN predeposition process can effectively improve the repeatability of AlN buffer layer growth. Moreover, the crystal quality of AlN is improved as well.

High‐Brightness GaN‐Based Blue Light‐Emitting Diodes Using AlON Buffer Layer on 4 In.‐Patterned Sapphire Substrate: Low‐Dislocation‐Defect Epitaxy, Growth Mechanisms, and Higher Device Performance

“…[28] The buffer layer between the sapphire substrate and the initial GaN layer is the key to reducing the density of TDs in the initial GaN layer. [29,30] Therefore, the analysis of dislocation density is one of the criteria for evaluating the quality of buffer layers. To determine the effect of AlON buffer layer fabricated using different oxygen flow rates, HRXRD was used to characterize the epilayer quality of the full LED structure.…”