Analysis of Characteristic Temperature for InGaAsP BH Lasers with p-n-p-n Blocking Layers Using Two-Dimensional Device Simulator

The threshold current and the characteristic temperature of 1.3m InGaAsP–InP buried heterostructure (BH) lasers with the p-n-p-n blocking layers have been numerically analyzed using a two-dimensional (2-D) device simulator. The simulation model includes optical gain, intervalence absorption, radiative spontaneous-emission current, Auger recombination current, Shockley–Read–Hall recombination current, and heterobarrier leakage current. In addition to these components, the leakage current flowing through the p-n-p-n blocking layer which was ignored so far is also included. The analysis of the current components reveals that the increase in the threshold current with temperature is due to Auger recombination and the leakage current through the p-n-p-n blocking layer. The calculated T0 value containing all the components is 54 K at room temperature and 29 K above 80 C; which is consistent with observed T0 values. When the leakage current through the p-n-p-n blocking layer is ignored in the calculation, the T0 value is improved to 90 K and a decrease in the T0 value is not observed. This result is consistent with conventional calculations. When Auger recombination is ignored, the T0 value increases to 110 K at room temperature. However, the threshold current increases beyond the exponential relationship Ith = I0 exp(T=T0) and the T0 value decreases to 34 K at high temperature. This is due to a large increase rate of the leakage current through the p-n-p-n blocking layer. The reduction of Auger recombination is effective in decreasing the threshold current while the reduction of the leakage current through the p-n-p-n blocking layer is effective in improving T0 values at high temperature, since T0 values correspond to the increase rate of the threshold current.