Thin GaN with a thickness of 0.5 mum on a Si (1 1 1) diode was grown using metal-organic chemical vapor deposition to fabricate a low-cost metal field effect transistor (MESFET). First, a 40 nm-thick AlGaN buffer was formed on Si (1 1 1) substrate. After that, a GaN film was grown on the buffer layer and homogeneous thin GaN without any crack was obtained. The MESFET was fabricated using a 0.5 mum-thick GaN film on a Si substrate without a high-resistance GaN layer. The Schottky electrode was Pt/Au and the ohmic electrode was Al/Ti/Au. As a result, 300degreesC operation of the MESFET was confirmed using a thin GaN film on a Si substrate for the first time. (C) 2003 Elsevier Science B.V. All rights reserved.