NEAR-IDEAL IV CHARACTERISTICS OF GAINP/GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS

GaInP/GaAs heterojunction bipolar transistors (HBT's) have been fabricated and these devices exhibit near-ideal I-V characteristics with very small magnitudes of the base-emitter junction space-charge recombination current. Measured current gains in both 6 x 6- and 100 X 100-mu-m2 devices remain constant for 5 decades of collector current and are greater than unity at ultrasmall current densities on the order of 1 x 10(-6) A/cm2. For the 6 x 6-mu-m2 device, the current gain reaches a high value of 190 at higher current levels. These device characteristics are also compared to published data of an abrupt AlGaAs/GaAs HBT having a base layer with similar doping level and thickness.