High-speed and high-light output power of InGaAs/GaAs HBLETs with an InMoO_x contact

A high-speed and high-light-output-power InGaAs/GaAs heterojunction bipolar light-emitting transistors (HBLETs) at 968-nm wavelength employing indium molybdenum oxide (IMO) contact are demonstrated in this letter. The IMO contact exhibits a low electrical resistivity of (3.5 × 10^-4 Ω)-cm accompanied with an extremely high optical transmittance of 99% at 968 nm, which can be ascribed to larger valence difference between In ³⁺ matrix and Mo⁶⁺ dopants. As compared to HBLET with conventional AuGe contact, HBLET with IMO contact shows a higher forward voltage and higher series resistance. However, at the corresponding injection current level, HBLET with IMO contact produces a light output power with a rate of (5.7~ μ ) W/mA, which is twice of (2.7~ μ ) W/mA for HBLET with AuGe contact. In addition, HBLET with IMO contact exhibits a 3-dB optical bandwidth of 649 MHz, which is correlated to a carrier recombination lifetime of 245 ps. The successful incorporation of an IMO contact into an HBLET can improve the optical output extraction significantly without the expense of losing modulation speed.