Premium
Band Structure Effects on the Transient Electron Velocity Overshoot in GaN
Author(s) -
Wraback M.,
Shen H.,
Bellotti E.,
Carrano J.C.,
Collins C.J.,
Campbell J.C.,
Dupuis R.D.,
Schurman M.J.,
Ferguson I.T.
Publication year - 2001
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200111)228:2<585::aid-pssb585>3.0.co;2-z
Subject(s) - velocity overshoot , wurtzite crystal structure , photoexcitation , heterojunction , electron , electric field , overshoot (microwave communication) , transient (computer programming) , materials science , wide bandgap semiconductor , optoelectronics , condensed matter physics , photodiode , effective mass (spring–mass system) , electronic band structure , saturation velocity , physics , atomic physics , optics , drift velocity , excited state , telecommunications , quantum mechanics , operating system , computer science , diffraction
Time‐resolved electroabsorption measurements on an AlGaN/GaN heterojunction p–i–n photodiode have been used to study the transient electron velocity overshoot for transport in the c ‐direction in wurtzite GaN. The velocity overshoot increases with electric field up to ∼320 kV/cm, at which field a peak velocity of 7.25 × 10 7 cm/s is attained within the first 200 fs after photoexcitation. However, theoretical Monte Carlo calculations incorporating a GaN full‐zone band structure show that the majority of electrons do not attain sufficient energy to effect intervalley transfer until they are subjected to higher fields (>325 kV/cm). Insight into this behavior can be gleaned from the band nonparabolicity deduced from the constant energy surfaces in the Γ valley, which shows that the effective mass in the c ‐direction can be viewed as becoming larger at high k values.