Relaxation of InGaN thin layers observed by X-ray and transmission electron microscopy studies

• Published in: Journal of electronic materials Vol. 30; no. 4; pp. 439 - 444
• Main Authors: LILIENTAL-WEBER, Z, BENAMARA, M, WASHBURN, J, DOMAGALA, J. Z, BAK-MISIUK, J, PINER, E. L, ROBERTS, J. C, BEDAIR, S. M
• Format: Conference Proceeding Journal Article
• Language: English
• Published: New York, NY Institute of Electrical and Electronics Engineers 01.04.2001; Springer Nature B.V
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Interfaces; Microelectronic fabrication (materials and surfaces technology); Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Quantum well; Quantum dot; Experimental study; Chemical vapor deposition; Gallium nitride; Planar defect; Thin film; Interface structure; Interface properties; Microelectronic fabrication; Experimental result; Transmission electron microscopy; MOVPE method; Strained layer; Indium nitride; X ray diffractometry; Microstructure
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-001-0056-5

Double-crystal and triple-axis x-ray diffractometry and transmission electron microscopy are used to characterize the microstructure, strain, and composition of InGaN layers grown on GaN by metalorganic chemical vapor deposition (MOCVD). Three different samples with increasing In concentration have been studied, all grown on GaN deposited on sapphire either with GaN or AlN buffer layers. It was found that InGaN layers with nominal 28% and 40% InN content consist of two sub-layers; the first sub-layer is pseudomorphic with the underlying GaN with lower In content than nominal. The top sub-layer is fully relaxed with a high density of planar defects and In content close to the nominal value. This is in contrast to a common assumption applied to InGaN quantum wells that 'quantum-dot like areas' are formed with different In content. The sample with the nominal indium concentration of 45% does not exhibit any intermediate strained layer, is fully relaxed and the In concentration (43.8%) agrees well with the nominal value.