Low-voltage charge-coupled devices with a heterostructure charge-storage well

Abstract

A CCD with an internal heterostructure well to store the photogenerated carriers is realized by using barrier and absorber semiconductors with a type-II band alignment in nBn or pBp photodetectors to form a specific barrier configured to confine the depletion region and a well to trap and store the photogenerated minority carriers. Depending on the spectral regime, (InAs/InAsSb)/(InAs/AlGaSb) superlattices can be used in the infrared, Si/Ge or AlP/GaP in the visible portion of optical spectrum, and GaN/ZnO in the UV portion. The resulting device not only leverages the advantages of the conventional CCD (such as in-pixel signal integration to suppress the noise), but also boasts an advantageously low operational voltage, thereby ensuring the low power consumption and low band-to-band tunneling current/noise (in particular, for use as an infrared photodetector). In comparison with IR FPAs of related art, the cost of the device is reduced and no flip-chip mount on a read-out integrated circuit is required during the fabrication process.