Variable area MWIR diodes on HgCdTe/Si grown by molecular beam epitaxy

Abstract

Molecular beam epitaxy technique has been used to grow double layer heterostructure mercury cadmium telluride materials on silicon substrates for infrared detection in the mid-wavelength infrared transmission band. Test structures containing square diodes with variable areas from 5.76 × 10⁻⁶ cm² to 2.5×10⁻³ cm² are fabricated on them. The p on n planar architecture is achieved by selective arsenic ion implantation. The absorber layer characteristics for the samples studied here include a full width at half maximum of 100–120 arcsec from x-ray rocking curve, the electron concentration of 1−2 × 10¹⁵ cm⁻³ and mobility 3−5 × 10⁴ cm²/V-s, respectively at 80 K from Hall measurements. The minority carrier lifetime measured by photoconductive decay measurements at 80 K varied from 1 to 1.2 µsec. A modified general model for the variable area I–V analysis is presented. The dark current-voltage measurements were carried out at 80 K and an analysis of the dependence of zero-bias impedance on the perimeter/area ratio based on bulk, surface generation-recombination, and lateral currents are presented. The results indicate state-of-the art performance of the diodes in the midwavelength infrared region.