In Al Ga As ∕ In P light-emitting transistors operating near 1.55μm

Abstract

Light-emitting transistors (LETs) operating at around 1.55μm were investigated using InP∕InAlGaAs heterostructures grown by metal organic chemical vapor deposition. By incorporating InGaAs quantum wells (QWs) in the base region of the N-InP∕p-InAlGaAs∕N-InAlAs heterojunction bipolar transistors, LET structures were achieved with a current gain of 45 and light emission at a wavelength of 1.65μm. The light output was found to be dependent on the base current. The larger the number of QWs incorporated in the base of the LETs, the larger the light output, with correspondingly reduced current gain. Secondary ion mass spectroscopy shows that the p-type dopant, zinc (Zn), which is commonly used in the growth of InAlGaAs, diffuses into the emitter and the base active QW region, leading to compromised electrical performance and light output intensity. Increasing the Zn doping level in the barrier layers of the QW structure causes the photoluminescence efficiency to decrease rapidly. Consequently, an alternative low-diffusivity dopant, carbon (C), was studied and a LET with a C-doped base was grown and fabricated. The highest light output was demonstrated for the C-doped LETs owing to the improved quality of the active layer.

Simulation of a 1550-nm InGaAsP-InP transistor laser

“…The heavily p-doped layer for the p contact is placed away below the QWs for preventing dopant diffusion into the QWs which can significantly affect the optical gain. 11 The p contact on InGaAsP might be challenging. In 0.53 Ga 0.47 As is widely used as the p contact layer in 1550 nm laser didoes although it has smaller band-gap than the QWs since it is usually far away from the active region.…”

Raman study of V/III flux ratio effect in InP/InAlAs/InP heterostructures grown by MOCVD

“…The InAlAs ternary alloy, lattice matched to InP substrates is potentially of importance owing to its usefulness for the fabrication of optoelectronic [3,4] and high-speed electronic [5,6] devices. While the AlGaAs/GaAs material system has an abrupt hetero-interface, [7,8] the growth of InAlAs on InP substrates has been reported to be difficult.…”