초록 ▼

A photodetector (10) of the non-equilibrium kind incorporates three successively disposed sections (14, 16, 18) of like layer construction. Each of the sections (e.g. 14) contains three layers (14A, 14B, 14C) of semiconductor materials of the CdxHg1-xTe alloy system (CMT). The central layer (14B) of

A photodetector (10) of the non-equilibrium kind incorporates three successively disposed sections (14, 16, 18) of like layer construction. Each of the sections (e.g. 14) contains three layers (14A, 14B, 14C) of semiconductor materials of the CdxHg1-xTe alloy system (CMT). The central layer (14B) of each section (14) is of narrow bandgap CMT, i.e. x=0.19 or 0.265 for absorption at 3-5 mm15 cm-3) providing intrinsic conductivity. It is 1.5 m14A, 14B) are 10 m16 cm-3 providing extrinsic conductivity. Each central layer (14B) is therefore bounded by an excluding contact (14AB) and an extracting contact (14BC), which depress its carrier concentration to an extrinsic level under the action of electrical bias. This simulates cooling to low temperature. The central layers (14B to 18B) have a collective thickness (4.5 mm20) is arranged to return through the photodetector (10) radiation transmitted by it. This presents a total active region thickness six times that of an individual central region (14B) and greater than an optical absorption length. The photodetector (10) consequently has high quantum efficiency despite the deficiencies of n-type CMT material in this regard.

대표청구항 ▼

A photodetector comprising a semiconductor multilayer structure (10) characterized in that the structure (10) has a plurality of successively disposed sections (14, 16, 18) each having three respective layers (e.g. 14A, 14B, 14C), the three layers consisting of a relatively narrow bandgap residual n

A photodetector comprising a semiconductor multilayer structure (10) characterized in that the structure (10) has a plurality of successively disposed sections (14, 16, 18) each having three respective layers (e.g. 14A, 14B, 14C), the three layers consisting of a relatively narrow bandgap residual n-type central layer (14B) sandwiched between relatively wide bandgap outer layers (14A, 14C) doped n-type and p-type respectively, the central layer (14B) being sufficiently thin to exhibit minority carrier extraction throughout its thickness when biased and having sufficiently low doping to exhibit intrinsic conductivity at an operating temperature when unbiased, and the outer regions (14A, 14C) being sufficiently thick to inhibit minority carrier injection into the central region (14B) and having sufficiently high doping to provide extrinsic conductivity at the operating temperature.