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Metal‐Insulator Transition in GaN Crystals
Author(s) -
Perlin P.,
Knap W.,
Camassel J.,
Polian A.,
Chervin J. C.,
Suski T.,
Grzegory I.,
Porowski S.
Publication year - 1996
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/pssb.2221980130
Subject(s) - materials science , metal–insulator transition , insulator (electricity) , condensed matter physics , optoelectronics , nanotechnology , metal , metallurgy , physics
By means of high‐pressure Raman spectroscopy of coupled LO phonon‐plasmon modes, a qualitatively new model of the metal‐insulator transition observed in bulk GaN crystals at pressure around 20 GPa is proposed. This transition was interpreted recently as caused by the emergence of the localized donor state into the energy gap of GaN. Our new experimental evidence suggests that two types of donors can supply electrons to the bulk crystal: the first of a localized character and the second of a shallow character with contributions to the electron concentration of 5 × 10 19 and 3 × 10 18 cm −3 , respectively. The localized state can be associated with the nitrogen vacancy, while the shallow state can be tentatively attributed to impurities such as oxygen. A number of interesting phenomena take place beyond the metal‐insulator transition in bulk GaN and an attempt to explain them will be made in the present work.