GROWTH AND CHARACTERIZATION OF P-ON-N HGCDTE LIQUID-PHASE EPITAXY HETEROJUNCTION MATERIAL FOR 11-18 MU-M APPLICATIONS

The capability of growing long-wavelength infrared HgCdTe liquid-phase epitaxy P-on-n heterojunction films with state-of-the-art photodiode performance, with excellent thickness uniformity (+/- 10%), and with excellent cutoff wavelength uniformity (e.g., 10.5 +/- 0.1-mu-m) across 2.5 cm x 4.0 cm wafers has been demonstrated. In addition, we have extended the region of HgCdTe photodiode operation to wavelengths of 18-19-mu-m at 80 K. Both measured carrier lifetime and photodiode data show that the n-type HgCdTe base layers are of excellent quality, with 77 K carrier lifetimes at the calculated Auger-1 limit for film carrier concentrations above 4 X 10(14) cm-3. The R0A products for large-area diodes (10(-3) cm2) with cutoff wavelengths of 11-19-mu-m are consistent with n-side diffusion current calculated using the film Auger-1 lifetime. Smaller diodes of area 1 x 10(-5) cm2 have typical R0A values of 12-OMEGA-cm2 at 80 K for a 12.2-mu-m cutoff wavelength. Large area diodes with an 80 K cutoff wavelength of 18-19-mu-m have R0A products of 0.14-OMEGA-cm2 at 80 K and 0.4-OMEGA-cm2 at 70 K. Quantum efficiency values of 60% are observed with no antireflection coating (corresponding to 75% internal quantum efficiency) and the spectral response data are classical.