Tunnel emitter transistors (TETs) are promising devices for high-current-density, high-frequency applications. The excellent CMOS compatibility of the TET makes it an ideal candidate to replace the bipolar junction transistors in BiCMOS technology; however, many properties of the TET are still under investigation. In this paper we present TETs with the highest current gain ever reported, 500-800. The effect of oxide quality on device performance is also described, and how the device characteristics can be improved by post-metallization annealing. Finally, we observe enhanced gain due to collecton-emitter avalanching. (C) 2002 Elsevier Science Ltd. All rights reserved.