Journal ArticleDOI
Polarization effects, surface states, and the source of electrons in AlGaN/GaN heterostructure field effect transistors
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In this paper, the origin of the two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructure field effect transistors is examined theoretically and experimentally.Abstract:
The origin of the two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructure field effect transistors is examined theoretically and experimentally. Based on an analysis of the electrostatics, surface states are identified as an important source of electrons. The role of the polarization-induced dipole is also clarified. Experimental Hall data for nominally undoped Al0.34Ga0.66N/GaN structures indicate that ∼1.65 eV surface donors are the actual source of the electrons in the 2DEG, which forms only when the barrier thickness exceeds 35 A.read more
Citations
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Journal ArticleDOI
Measurement of the variable surface charge concentration in gallium nitride and implications on device modeling and physics
E. Ber,B. Osman,Dan Ritter +2 more
TL;DR: In this paper, the density of interface trap states (Dit) at the surface of a GaN/AlGaN/GaN heterojunction was evaluated by the previously described gated van der Pauw experiments.
Journal ArticleDOI
Electronic transitions and fermi edge singularity in polar heterostructures studied by absorption and emission spectroscopy
Saurabh Pandey,Daniela Cavalcoli,Albert Minj,Beatrice Fraboni,Anna Cavallini,Piero Gamarra,M. A. Poisson +6 more
TL;DR: In this paper, the energy levels within the two dimensional electron gas (2DEG) well at the interface between the GaN and AlN have been directly observed by surface photovoltage (SPV), photocurrent (PC), and photo luminescence spectroscopy.
Journal ArticleDOI
Role of Surface States and Interface Charges in 2DEG in Sputtered ZnO Heterostructures
TL;DR: In this paper, the influence of surface (donor and acceptor) states and interface charges on the formation of 2-D electron gas (2DEG) in MgZnO and ZnO heterostructures grown by sputtering is reported.
Journal ArticleDOI
Reduction of contact resistance on AlGaN/GaN HEMT structures introducing uneven AlGaN layers
Yusuke Takei,Masayuki Kamiya,Kazuo Tsutsui,Wataru Saito,Kuniyuki Kakushima,Hitoshi Wakabayashi,Yoshinori Kataoka,Hiroshi Iwai +7 more
TL;DR: In this paper, a new technique to reduce contact resistance on AlGaN/GaN HEMTs was proposed, which introduced uneven GaN layer structures and demonstrated the effectiveness of this technique.
References
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Journal ArticleDOI
Spontaneous polarization and piezoelectric constants of III-V nitrides
TL;DR: In this paper, the spontaneous polarization, dynamical Born charges, and piezoelectric constants of the III-V nitrides AlN, GaN, and InN are studied ab initio using the Berry-phase approach to polarization in solids.
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Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures
Oliver Ambacher,Joseph A. Smart,James R. Shealy,Nils Weimann,K. Chu,M. J. Murphy,William J. Schaff,L.F. Eastman,Roman Dimitrov,L. Wittmer,Martin Stutzmann,W. Rieger,J. Hilsenbeck +12 more
TL;DR: In this article, the authors investigated the role of spontaneous and piezoelectric polarization on the carrier confinement at GaN/AlGaN and AlGaN/GaN interfaces.
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Quantum-Confined Stark Effect due to Piezoelectric Fields in GaInN Strained Quantum Wells
Tetsuya Takeuchi,Shigetoshi Sota,Maki Katsuragawa,Miho Komori,Hideo Takeuchi,Hiroshi Amano,Isamu Akasaki +6 more
TL;DR: In this article, the influence of piezoelectric fields on luminescence properties of GaInN strained quantum wells was studied and it was shown that an electric field of 1.08 MV/cm is induced by the piezolectric effect in strained Ga0.87In0.13N grown on GaN.
Journal ArticleDOI
Valence‐band discontinuities of wurtzite GaN, AlN, and InN heterojunctions measured by x‐ray photoemission spectroscopy
TL;DR: In this paper, the valence band discontinuities at various wurtzite GaN, AlN, and InN heterojunctions were measured by means of x-ray photoemission spectroscopy.
Journal ArticleDOI
Very high breakdown voltage and large transconductance realized on gan heterojunction field effect transistors
Yifeng Wu,Bernd Keller,Stacia Keller,D. Kapolnek,Peter Kozodoy,Steven P. DenBaars,Umesh K. Mishra +6 more
TL;DR: In this article, the authors reported record high breakdown voltages up to 340 and 230 V realized on unintentionally doped (1.5 μm gate length) and Si doped(1 μm/GaN modulation doped field effect transistors (MODFETs), respectively.