Anomalous behavior of stripe-geometry GaAs DH lasers at low temperatures

Our experiment shows that the threshold current of the lasers decreases with the lowering of temperature, and finally enters a saturation region. This is essentially consistent with Hwang's result in the range of 10--300 K. However, further lowering in temperature increases threshold current of the lasers. We believe that this increase is caused by the leakage of charge carriers. When the temperature is in the range of 2.8--6 K, the threshold current, the junction voltage and the dynamic resistance all exhibit structural regularities. If electron-hole liquid droplets have been found in this process, such anomaly may be explained qualitatively by the Landau's phase diagram. On the other hand, the possibility of the effect of impurity energy band can not be excluded.