Improving the CSIP performance

A novel highly sensitive detector for long wavelength infrared radiation, called charge sensitive infrared phototransistor (CSIP), is described, with a stress put on the report of recent improvements in the quantum efficiency. Metallic antenna structure placed on the surface to convert incident radiation has to be optimized. In case of the CSIP, where the absorbing quantum well is very close (∼100 nm) to the antenna, near field effects have to be taken into consideration. We consider several patterns based either on a double capacitive (dot) or inductive (hole) grating. We present results of a study comparing four different geometries showing that cross shape hole arrays are most promising candidates reaching efficiencies of almost 8%. Further strategies to optimize essential parameters of antennas by using finite difference time domain (FDTD) simulations are considered.