Design and performance analysis of extended wavelength InGaAs near-infrared photodetectors

In this work, we investigate the performance of InGaAs p–i–n photodetectors with cut-off wavelengths near 2.5 µm. The influences of different cap materials on the optoelectronic properties of InGaAs detector are also compared and discussed. The result indicates that the InAlAs used as cap layer can lead to lower dark current and larger quantum efficiency than other cap layers. In addition, our results show that the device performance is influenced by the valence band offset. This work proves that InAlAs/InGaAs/InP structure is a promising candidate for high performance detector with optimally tuned band gap. Furthermore, dark current mechanisms for extended wavelength InGaAs detectors are analyzed in-depth.