850 nm VCSEL with sub quantum well and p-type δ-doping in the active layers for improved high-speed and high-temperature performance

Thermal rollover is one of the fundamental limitations that affect the output power and modulation bandwidth of high-speed laser in monolithic laser integrated circuits (ICs). Herein, an 850 nm vertical cavity surface emitting laser (VCSEL) with p-doping and sub quantum well (sub QW) centers active layer is proposed and investigated. The p-doping and sub QW insert in the offset position of each barrier, which are designed for reducing the thermal rollover and increasing the maximum intrinsic modulation bandwidth of the laser. Numerical simulations show that adding the p-doping and sub QW in active region could reduce the threshold currents (Ith), improve the slope efficiency (SE) and delay the thermal rollover in VCSEL. Comparing with previous VCSEL, our proposed VCSEL has excellent high temperature output performance, and the maximum simulation 3-dB bandwidth is 43.9 at 25 °C and 33.1 GHz at 85 °C, respectively. Furthermore, temperature-dependent time-resolved photoluminescence (PL) and PL excitation reveal this novel QW has strong radiative recombination rate, which is suitable for designing active region of high-speed and high power lasers. • We designed a composite MQWs, with sub QW insert layer and p-type δ -doping, to improve the modulation speed of 850 nm VCSEL at high temperature operation. • Through Crosslight PICS3D simulation, the proposed composite MQWs could reduce the thermal roll-over and increase the maximum intrinsic modulation bandwidth of VCSEL. • Combining this composite MQWs with six oxide layer VCSEL, the maximum simulation 3 dB bandwidth could reach to 43.9 and 33.1 GHz at 25 ℃ and 85 ℃, respectively. • The high quality QW structure has been grown by using MBE system. The carrier dynamic properties showed that this novel QW has strong radiation recombination rate.