Role of p-doping profile and regrowth on the static characteristics of 1.3-μm MQW InGaAsP-InP lasers: experiment and modeling

In this paper, we study both experimentally and theoretically how the change of the p-doping profile, particularly the p-i junction placement, affects the output characteristics of 1.3-μm InGaAsP-InP multiple-quantum-well (MQW) lasers. The relationship between the p-doping profile before and after regrowth is established, and the subsequent impact of changes in the p-i junction placement on the device output characteristics, is demonstrated. Device characteristics are simulated including carrier transport, capture of carriers into the quantum wells, the quantum mechanical calculation of the properties of the wells, and the solution for the optical mode and its population self-consistently as a function of diode bias. The simulations predict and the experiments confirm that an optimum p-i junction placement simultaneously maximizes external efficiency and minimizes threshold current. Tuning of the base epitaxial growth Zn profile allows one to fabricate MQW devices with a threshold current of approximately 80 A/cm² per well for devices with nine QW's at room temperature or lasers with a characteristic temperature T₀ = 70 K within the temperature range of 20°C-80°C.