Development of Large-Area Imaging Arrays Using Epitaxially Grown Thick Single Crystal CdTe Layers on Si Substrates

Optimization of CdTe crystal growth by adjusting effective Te/Cd ratio at the growth surface, as well as growth-interrupted annealing together with detector array fabrication techniques were studied to achieve large-area, uniform x-ray spectroscopic imaging arrays. The p-CdTe/n-CdTe/n⁺-Si heterojunction diode-type detector arrays were fabricated by using epitaxially grown thick single crystal CdTe layers on n⁺-Si substrates, where pixels were patterned by making deep vertical cuts on p-CdTe side using a dicing saw. The study was first focused on development of 2D (8 × 8) array using 12.6 mm × 11.4 mm size wafers, which confirmed uniform dark current distribution among the pixels. We further demonstrated possibility of making larger arrays by fabricating (18 × 18) array using a 25 mm × 25 mm size uniform single crystal CdTe epilayer grown on Si substrate.