Passivation effect on optical and electrical properties of molecular beam epitaxy-grown HgCdTe/CdTe/Si layers

Abstract

The effects of passivation with two different passivants, ZnS and CdTe, and two different passivation techniques, physical vapor deposition (PVD) and molecular beam epitaxy (MBE), were quantified in terms of the minority carrier lifetime and extracted surface recombination velocity on both MBE-grown medium-wavelength ir (MWIR) and long-wavelength ir HgCdTe samples. A gradual increment of the minority carrier lifetime was reported as the passivation technique was changed from PVD ZnS to PVD CdTe, and finally to MBE CdTe, especially at low temperatures. A corresponding reduction in the extracted surface recombination velocity in the same order was also reported for the first time. Initial data on the 1/f noise values of as-grown MWIR samples showed a reduction of two orders of noise power after 1200-Å ZnS deposition.

Comparative Study of HgCdTe Etchants: An Electrical Characterization

“…Surface recombination velocities were extracted from the data at 78 K using a similar procedure as discussed in our last work. 11 All the variables used in Eq. 2 are explained in details in Ref.…”

“…In HgCdTe, ZnS and CdTe or a stack of both has been established as potential candidates for passivants, [8][9][10] and there have been a few studies which have dealt with comparisons among these passivants. 11 However, the surfaces are needed to be freshly etched and properly treated before passivation, which helps passivant molecules to search for the lowest energy surfaces resulting in a superior quality passivation film. As surface gets affected differently for different etchants, that can also affect the passivation quality and hence the device characteristics.…”

Design and fabrication of HgCdTe linear avalanche devices with low gain normalized dark current density

“…By optimizing the plasma atomic enhanced layer deposition (PEALD) Al2O3 film growing process, the surface leakage current of device is significantly suppressed. As we can see, the device of mesa structure with new combining dry/wet etching technology and passivation technology based on PEALD exhibits the best GNDCD performance, corresponding to GNDCD=1.71×10 -9 A/cm 2 @10V, which is almost two orders of magnitude lower than that of the device of planar structure with conventional CdTe/ZnS double-layer passivation technology [18][19].…”

“…Figure 6. The dark current density as a function of P/A ratios for devices of three passivation methods Figure 7 shows The measured GNDCD of HgCdTe APD test units by different desigin or fabrication processes.As we can see, the device of mesa structure with new combining dry/wet etching technology and passivation technology based on PEALD exhibits the best GNDCD performance, corresponding to GNDCD=1.71×10 -9 A/cm 2 @10V, which is almost two orders of magnitude lower than that of the device of planar structure with conventional CdTe/ZnS double-layer passivation technology[18][19].…”