Growth Temperature Dependency of High Al Content AlGaN Epilayers on AlN/Al2O3 Templates

Abstract

In this work, MOVPE (Metalorganic Vapor Phase Epitaxy) growth and characterization studies of high Al content AlGaN epilayers are reported. We utilize high resolution X-ray diffraction (HRXRD) and atomic force microscope (AFM) techniques to analyze the crystalline quality and surface morphology of AlGaN epilayers. The role of the growth temperature of AlGaN epilayers on the structural quality and the surface morphology was investigated. Growth and measurement results show that single phase AlGaN epilayers were grown on AlN/Al 2 O 3 template. It is concluded that the increasing growth temperature increases the Al content of AlGaN epilayers which enable to control the alloy concentration of AlGaN. Furthermore, the increasing Al content in AlGaN epilayers leads to the smooth surface which indicates that the decreasing number of dislocation density. Özet. Bu çalışmada, yüksek Al içerikli AlGaN epi-tabakaların MOVPE (Metalorganik Buhar Fazı Epitaksi) büyütmesi vekarakterizasyon çalışmaları rapor edilmiştir. AlGaN epi-tabakaların kristal kalitesi ve yüzey morfolojisi analizi için yüksek çözünürlüklü X-ışını kırınımı (HRXRD) ve atomik kuvvet mikroskobu teknikleri kullanılmıştır. Büyütme sıcaklığının AlGaN epi-tabakalarının yapısal kalitesi ve yüzey morfolojisi üzerindeki rolü incelenmiştir. Büyütme ve ölçüm sonuçları AlN/Al2O3 şablonu üzerine tek fazda AlGaN epi-tabakaların büyütüldüğünü göstermektedir. Artan büyütme sıcaklığının AlGaN'in Al içeriğini arttırdığı ve bunun AlGaN alaşım konsantrasyonunu kontrol etmeye olanak sağladığı sonucuna varılmıştır. Ayrıca, AlGaN epi-tabakalarındaki Al içeriğinin artışı pürüzsüz yüzeye yol açar ki bu dislokasyon yoğunluğunun azaldığını belirtir.

285 nm AlGaN-BASED DEEP-ULTRAVIOLET LED WITH HIGH INTERNAL QUANTUM EFFICIENCY: COMPUTATIONAL DESIGN

“…For example, the higher the Al amount, the more dislocations appear in practice yielding adverse effects on the required optical properties [15]. Besides, low mismatch percent for the layers is important in crystal growth and the AlGaN-based LED structure with the AlN buffer layer examined in this paper can be grown on sapphire (Al 2 O 3 ) as it is often reported in the literature [16][17][18][19][20]. The various difficulties encountered during the production process apart from the ones mentioned, such as point defects, cracking issues, low hole concentration, junction heating effect, and low light extraction efficiency (LEE) should not be ignored as well [7].…”

The GaN Epilayer Grown by MOVPE: Effect of The Different Nucleation Layer Temperatures

“…The III-Nitride based semiconductors have attracted great attention for recent years because of many important application areas in technological devices [1]. Their application areas are listed as high electron mobility transistors (HEMTs), solar-blind detectors, detectors of ionizing radiation and scintillators, UV emitters for purification, curing and disinfection, light-emitting, and lasers diodes [2][3][4][5][6][7][8][9][10][11]. Especially, the GaN grown via Metal Organic Vapour Phase Epitaxy (MOVPE) is the most popular of the III-Nitride based semiconductors (AlN, InN, and their alloys) [12].…”

AlGaN/AlN MOVPE heteroepitaxy: pulsed co-doping SiH4 and TMIn

“…Previously, we reported growth details of high quality PALE (pulsed atomic layer epitaxy) AlN on sapphire and silicon substrates. [13][14][15][16]. Besides the AlN template properties, the crystalline and morphological quality of Al x Ga 1−x N epilayers in active layers and contact layers are also significantly affect the device performances [17][18][19].…”