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Photoconductivity and Electroreflectance Study of Cubic GaN/GaAs(001) Heterostructures by Optical‐Biasing Technique
Author(s) -
Katayama R.,
Kuroda M.,
Onabe K.,
Shiraki Y.
Publication year - 2002
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(200212)234:3<877::aid-pssb877>3.0.co;2-h
Subject(s) - heterojunction , materials science , metalorganic vapour phase epitaxy , biasing , exciton , epitaxy , optoelectronics , photoconductivity , condensed matter physics , layer (electronics) , voltage , nanotechnology , physics , quantum mechanics
Photoconductivity (PC) and electroreflectance (ER) spectrum measurements were carried out for the cubic GaN/GaAs and cubic AlGaN/GaN/GaAs heterostructures grown by LP‐MOVPE. Both spectra contained significantly overlapped signals from the c‐(Al)GaN epitaxial layer and the underlying GaAs layer, but the latter was successfully suppressed and distinguished from the former by the use of an additional steady‐state illumination of Ar + laser as an optical bias. The temperature dependence of the optically‐biased PC spectrum showed that there remained structural disorder in the c‐GaN layer indicated by the temperature‐independent Urbach energy. From the temperature dependence of the ER spectrum, the E 0 critical point of c‐GaN observed likely corresponds not to excitonic transition but to free‐carrier transition as it shifted by ∼30 meV to higher energies than the reported value, probably due to the dissociation of exciton by the relatively large modulation field applied to the c‐(Al)GaN layer.