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Performance Enhancement of Microwave GaN HEMTs Without an AlN-Exclusion Layer Using an Optimized AlGaN/GaN Interface Growth Process

Johan Bergsten (Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik) ; J. T. Chen ; Sebastian Gustafsson (Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik) ; Anna Malmros (Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik) ; U. Forsberg ; Mattias Thorsell (Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik) ; E. Janzen ; Niklas Rorsman (Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik)
IEEE Transactions on Electron Devices (0018-9383). Vol. 63 (2016), 1, p. 333-338.
[Artikel, refereegranskad vetenskaplig]

The impact of the sharpness of the AlGaN/GaN interface in high-electron mobility transistors (HEMTs) is investigated. Two structures, one with an optimized AlGaN/GaN interface and another with an unoptimized, were grown using hot-wall metal-organic chemical vapor deposition. The structure with optimized sharpness of the interface shows electron mobility of 1760 cm(2)/V . s as compared with 1660 cm(2)/V . s for the nonoptimized interface. Gated Hall measurements indicate that the sharper interface maintains higher mobility when the electrons are close to the interface compared with the nonoptimized structure, indicating less scattering due to alloy disorder and interface roughness. HEMTs were processed and evaluated. The higher mobility manifests as lower parasitic resistance yielding a better dc and high-frequency performance. A small-signal equivalent model is extracted. The results indicate a lower electron penetration into the buffer in the optimized sample. Pulsed-IV measurements imply that the sharper interface provides less dispersive effects at large drain biases. We speculate that the mobility enhancement seen AlGaN/AlN/GaN structures compared with the AlGaN/GaN case is not only related to the larger conduction band offset but also due to a more welldefined interface minimizing scattering due to alloy disorder and interface roughness.

Nyckelord: AlGaN/GaN interface, GaN high-electron mobility transistor (HEMT), interface sharpness



Denna post skapades 2016-01-21.
CPL Pubid: 231073

 

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Institutioner (Chalmers)

Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik

Ämnesområden

Elektroteknik och elektronik

Chalmers infrastruktur