Investigation of InGaAs/GaAs Quantum Well Lasers with Slightly Doped Tunnel Junction

We experimentally investigate and analyze the electrical and optical characteristics of InGaAs/GaAs conventional quantum well laser diode and the quantum well laser diode with slightly-doped tunnel junction. It was found that the laser with slightly-doped tunnel junction has a nonlinear S-shape current-voltage characteristic. The internal quantum efficiencies of the laser with slightly-doped tunnel junction and the conventional laser are 21 and 87.3%, respectively. This suggests that the slightly-doped tunnel junction increased the barrier width and free carrier absorption, thus could reduce the electron tunneling probability and increase the internal loss. Furthermore, compared with the conventional laser, it was found that we could achieve 15 nm broadband spectrum from the laser with slightly-doped tunnel junction, due to the lasing dynamics reflecting the current dynamics. The results show that the slightly-doped tunnel junction plays a crucial role in the laser diode performances, which may lead to the realization of more applications.