Infra-Red Photodiodes in Hg1-xCdxTe Grown by OMVPE

ABSTRACTHg1-xCdxTe layers, grown by the organometallic vapor phase epitaxy (OMVPE), are p-type with carrier concentrations around 4 × 1016/cm3 due to the Group II vacancies in them. Following a Hg saturated anneal at 220°C, these layers become n-type with carrier concentrations around 4 × 1014/cm3. In order to fabricate p-n junction diodes, Hg1-xCdxTe layers were grown with a 0.5–0.8 μm thick CdTe cap. By opening windows in this CdTe cap, the underlying Hg1-xCdxTe Te layer was annealed in a selective manner, thus forming planar p-n junctions. The CdTe cap, which is used as the diffusion barrier for Hg during the selective anneal, also served as the junction passivant for the photodiodes. Details of device fabrication and characterization are presented in this paper.