A superlattice infrared photodetector integrated with multiple quantum wells to improve the performance

An infrared photodetector using the structure of a 15-period superlattice (SL) integrated with 50-period multiple quantum wells (MQWs) is investigated. The MQWs are utilized to reduce the noise current power and to add the response range. From the results of current ratio and response, the photocurrent of the SL is not reduced by the additional MQWs but the dark current is. Hence, due to the low noise gain and low dark current, the maximum detectivity (D*) can occur at low negative bias. In addition, the photovoltaic response even appears at 80 K. It is observed that the photoelectron transport directions from the SL and the MQWs are opposite under zero bias. In comparison with the SL with a single barrier, this structure also demonstrates the higher photocurrent and lower dark current. From our experimental results, this structure is appropriate for the operation at low bias and high temperature. However, the tradeoff is the small operational voltage range.