Sidewall effects of MBE grown CdTe for MWIR HgCdTe photoconductors

The semiconductor-passivating layer interfaces, as well as their dielectric properties, play important and very often dominant roles in determining HgCdTe device performance. In this work, photoconductors were fabricated on p-type mid-wave infrared Hg_1-xCd_xTe material using molecular beam epitaxy (MBE) grown CdTe film as the passivation layer. In order to emphasize the importance of the CdTe passivating layer, HgCdTe photoconductors with and without the sidewall CdTe passivation were fabricated. The photoconductor with its sidewalls passivated shows significantly higher responsivity than the one without sidewall passivation. Conductance-voltage characteristics of capacitor using CdTe between HgCdTe and metal contacts were made in studying insulating property of the passivation film. Scanning electron microscopy (SEM) micrographs and X-ray diffraction (XRD) spectra were included in order to investigate the structural properties of the CdTe passivation film.