Role of the defect microstructure on the electrical transport properties in undoped and Si-doped GaN grown by LP-MOVPE

Experimental results show that the room-temperature carrier mobility in bul k layers of undoped or Si-doped GaN grown by LP-MOVPE on sapphire substrate shows a sudden increase as soon as the carrier density exceeds a critical value of about 10(18) cm(-3). We show that such a behavior can be theoretic ally reproduced by assuming that the columnar structure i.e. the dislocatio n microstructure is responsible for internal electronic barriers. (C) 1999 Elsevier Science B.V. All rights reserved.