Preparation of low-resistance tunnel junction for high efficiency multi-junction semiconductor laser diodes

Low reverse-bias series resistance tunnel junctions (TJs) are the key to improving the performances of high efficiency multi-junction semiconductor laser diodes (MJLDs). In this paper, InGaAs QW TJ and InGaAs DQW TJ with single InGaAs layer and double InGaAs layers inserted into GaAs TJs separately, are proposed. TJ chips were fabricated by metal organic chemical vapor deposition (MOCVD) technology and semiconductor process. The measurement results of the devices display that the operating voltage of the InGaAs QW TJ and the InGaAs DQW TJ is lower than that of the GaAs TJ under the same injection current, whether it is a small current or a large current, and the InGaAs DQW TJ operating voltage is lower than that of the InGaAs QW TJ. Both GaAs TJ and InGaAs DQW TJ were applied to 1060 nm dual active region semiconductor laser diode. The ridge lasers with a strip width of 100μm and a cavity length of 2 mm were fabricated. The working voltage is reduced from 3.81 V to 3.38 V at 1 A drive current. Further experimental results indicate that the reverse-bias series resistance of InGaAs QW TJ and InGaAs DQW TJ is lower than that of GaAs TJ, and the performances of InGaAs DQW TJ are the best. This is of great significance to reduce the heat loss of MJLDs and improve its performances.