Development and Characterization of GaInP/GaAs HBTs for High Voltage Operation
P. Kurpas, F. Brunner, W. Doser*, A. Maaßdorf, R. Doerner
M. Rudolph, H. Blanck*, W. Heinrich, and J. Würfl
Ferdinand-Braun-Institut für Höchstfrequenztechnik (FBH)
* United Monolithic Semiconductors GmbH
This paper reports on the development of GaInP/GaAs HBTs suitable for high-voltage operation.

First, the dependence of breakdown voltages on thickness and doping level of the collector layer is determined. High BVcbo and BVceo values of 69V and 41V, respectively, are obtained for a 2.8µm thick collector doped to 4x1015 cm-3.

The required process modifications for this very high device topology are described. The fabricated high-voltage HBTs show DC characteristics comparable to our "standard" low-voltage HBTs. However, a limitation in usable current density becomes visible at higher voltages due to the lack of electrical ballasting and insufficient heat sinking of these devices. fT and fmax values of 24 GHz and 50 GHz, respectively, document good RF performance. A comparably small HBT power cell with 10x3x30 µm2 emitter area delivers 2.2W of microwave power with a high PAE of 66% at 2 GHz and 20V bias voltage.