Sharp Interface Blocked Impurity Band Very Long-Wavelength Infrared Photodetector With High-Temperature Epitaxy

The Silicon-based blocked impurity band (BIB) very long-wavelength infrared photodetector has been successfully used in astronomical infrared detection. In the traditional simulation model of BIB, a clear interface between the highly doped absorbing layer and the intrinsic blocking layer is a foundational assumption. However, achieving precise control over the interface remains a significant challenge in existing growth techniques. Here, we proposed a high-temperature epitaxial blocking layer method based on molecular beam epitaxy. This technique incorporates the sticking activation energy and diffusion coefficient of Gallium. After the epitaxial growth of the absorbing layer, the substrate temperature of the epitaxial blocking layer is increased to decrease the sticking coefficient and prevent the memory effect of Ga, thereby realizing a sharp interface layer. Photodetector developed using wafers grown epitaxially through this method exhibits a dark current below 1 pA and can effectively detect wavelengths up to
$20~\mu \text{m}$
. This letter not only introduces a new growth methodology for BIB but also offers a strategy to attain the ideal BIB structure.