InGaP/GaAs pnp Heterojunction Bipolar Transistor with δ-Doped Sheet between Base-Emitter Junction
In this article, a novel InGaP/GaAs pnp δ-doped heterojunction bipolar transistor is first demonstrated. Though the valence band discontinuity at InGaP/GaAs heterojunction is relatively large, the addition of a δ-doped sheet between two spacer layers at the emitter-base junction effectively eliminates the potential spike and increases the confined barrier for electrons, simultaneously. Experimentally, a high current gain of 25 and an offset voltage of 100 mV are achieved. The offset voltage is much smaller than the conventional InGaP/GaAs pnp HBT. The proposed device could be used for linear amplifiers and low-power complementary integrated circuit applications.
Prof. Alan Kin Tak Lau, Dr. J. Lu, Vijay K. Varadan, Fu-Kuo Chang, J.P. Tu and Pou Man Lam
J. H. Tsai et al., "InGaP/GaAs pnp Heterojunction Bipolar Transistor with δ-Doped Sheet between Base-Emitter Junction", Advanced Materials Research, Vols. 47-50, pp. 383-386, 2008