Temperature-dependent hall measurement of AlGaN/GaN heterostructures on Si substrates

• Published in: Journal of the Korean Physical Society Vol. 66; no. 1; pp. 61 - 64
• Main Authors: Lee, In Hak, Kim, Yong Hyun, Chang, Young Jun, Shin, Jong Hoon, Jang, T., Jang, Seung Yup
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Physical Society 01.01.2015; 한국물리학회
• Subjects: Mathematical and Computational Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Theoretical; 물리학; High electron mobility transistor; GaN, Hall measurement; Impurity scattering
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.66.61

For AlGaN/GaN high electron mobility transistor (HEMT) devices grown on Si substrates, we studied the influence of the surface defect density on the Hall mobility and the carrier concentration. We established a Hall measurement system over wide temperature range (8 ~ 800 K) by combining a closed-cycle refrigerator and a heating chamber. The two-dimensional electron gas (2DEG) in the epitaxially-grown AlGaN/GaN HEMT structures showed high mobilities, i.e ., > 1500 cm 2 /Vs at 300 K and > 7000 cm 2 /Vs at 8 K. As the surface defect density increased, the mobility values at 8 K decreased due to scattering from charged impurities at low temperatures. However, at high temperatures where optical phonons are a major source of scattering, the mobilities do not show a significant dependence on the surface defect density. In addition, the carrier density showed an unexpected decrease at temperatures above 300 K, which is ascribed to a change in the misfit strain upon heating.