Current-voltage and light-current characteristics in highly strained InGaAs/InAlAs quantum cascade laser structures

Growth of electroluminescent devices based on strain-compensated In_xGa_1-xAs/In_yAl_1-yAs has been undertaken. The very high conduction band offset of the strained material allows the design of such devices with very short emission wavelength. Device design and material characterisation for 2 μm emission has been undertaken. An analysis of the direct current amplitude modulation response of the strained structure is also performed. Strong room temperature emission with peaks around 1.55 μm dependent upon driving current has been observed under continuous wave reverse operational bias. This reverse bias emission was observed owing to the presence of interface states. Moreover experimentally measured current-voltage characteristics in forward bias are found to be in good agreement with theoretical predictions.