Optical properties of Zn-diffused InP layers for the planar-type InGaAs/InP photodetectors *Project supported by the Key R&D Program of Jiangsu Province (No. BE2016085), the National Natural Science Foundation of China (Nos. 61674051), and the External Cooperation Program of BIC, Chinese Academy of Sciences (No. 121E32KYSB20160071). (December 2017) - Chen, Guifeng
Abstract: Zn diffusion into InP was carried out ex-situ using a new Zn diffusion technique with zinc phosphorus particles placed around InP materials as zinc source in a semi-closed chamber formed by a modified diffusion furnace. The optical characteristics of the Zn-diffused InP layer for the planar-type InGaAs/InP PIN photodetectors grown by molecular beam epitaxy (MBE) has been investigated by photoluminescence (PL) measurements. The temperature-dependent PL spectrum of Zn-diffused InP samples at different diffusion temperatures showed that band-to-acceptor transition dominates the PL emission, which indicates that Zn was commendably diffused into InP layer as the acceptor. High quality Zn-diffused InP layer with typically smooth surface was obtained at 580 °C for 10 min. Furthermore, more interstitial Zn atoms were activated to act as acceptors after a rapid annealing process. Based on the above Zn-diffusion technique, a 50 μ m planar-type InGaAs/InP PIN photodector device was fabricated and exhibited a low dark current of 7.73 pA under a reverse bias potential of −5 V and a high breakdown voltage of larger than 41 V ( I < 10 μ A). In addition, a high responsivity of 0.81 A/W at 1.31 μ m and 0.97 A/W at 1.55 μ m was obtained in the developed PIN photodetector.