0.25-µm-Emitter InP Heterojunction Bipolar Transistors with a Thin Ledge Structure

• Published in: Japanese Journal of Applied Physics Vol. 49; no. 4S; p. 4
• Main Authors: Kashio, Norihide, Kurishima, Kenji, Fukai, Yoshino K., Ida, Minoru, Yamahata, Shoji
• Format: Journal Article
• Language: English
• Published: 01.04.2010
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.49.04DF02

This paper describes 0.25-µm-emitter InP heterojunction bipolar transistors (HBTs) with a thin ledge structure. The HBTs consist of a degenerately-doped n + -InGaAs/15-nm-thick undoped InP emitter, a 25-nm-thick p + -In 0.53 Ga 0.47 As base, and a 75-nm-thick In 0.53 Ga 0.47 As collector. The emitter enables fabrication of a 15-nm-thick ledge structure simply by wet etching the n + -InGaAs emitter. The emitter mesa and base metal were scaled down to 0.25 and 0.3 µm, respectively. The fabricated HBT with a 0.25-µm emitter provides a current gain of 62 at a collector current density, J c , of 10 mA/µm 2 . With the thin ledge structure, the current gain is virtually independent of emitter size and emitter–base spacing. The HBT also exhibits an f t of 442 GHz and an f max of 214 GHz at a J c of 12 mA/µm 2 . The results of bias-temperature stress tests show that base and collector currents are stable up to 1042 h at a J c of 5 mA/µm 2 .