Large negative magnetoresistance induced by interplay between smooth disorder and antidots in AlGaN/GaN HEMT structures. (22nd April 2016)

• Record Type: Journal Article
• Authors: Mishra, M K; Sharma, R K; Tyagi, R; Manchanda, R; Pandey, A K; Thakur, O P; Muralidharan, R
• Is Part Of: Materials research express. Volume 3:Number 4(2016)
• Publication Date: 2016-04-22
• Subjects: AlGaN/GaN HEMT -- magnetotransport -- Shubnikov de Haas oscillations; Materials science -- Research -- Periodicals; Materials science -- Periodicals; 620.11
• DOI: 10.1088/2053-1591/3/4/045902
• Languages: English
• ISSNs: 2053-1591

Abstract

Abstract: Large low temperature negative magnetoresistance (NMR) experimentally observed in AlGaN/GaN high electron mobility transistors (HEMT) structures grown by metalorganic chemical vapour deposition on sapphire substrate has been reported. A linear B − 1 ln B dependence of magnetoresistance observed in our samples indicates the presence of random antidot array together with smooth disorder. It is proposed that the antidots are linked with high bandgap AlN rich regions formed due to possible Al–Ga segregation at the interface during growth and the smooth random disorder is due to interface roughness. The antidot density is estimated to be of ∼7 to 8 × 10 10 cm −2 in our samples. The magnitude of NMR is also correlated with the extent of interface roughness indicated by x-ray reflectivity. It is also proposed that the formation of antidots is related with the lattice mismatch between substrate and epitaxial heterostructures. The NMR in AlGaN/GaN HEMT structures grown on SiC substrates having relatively lower lattice mismatch has been shown to have a usual B 2 and ln T dependences indicating only electron–electron interaction and absence of antidot-like scatterers.