Abstract
A very-far infrared bolometer detector operated at pumped-LHe temperatures has been developed and exhibits a relatively high-responsivity, high-speed performance, together with a low value of the NEP. The operation of the element is based on the “hopping” conductivity of holes between acceptor sites in single-crystal, p-type compensated Ge containing 9 × 10 15/cm 3 Ga impurities and 1 × 1O 15/cm 3 Sb impurities, for a compensation ratio K = 0.11. The element has a negative thermal coefficient of resistance α = 2.24 (°K) −1 at 1 65° K. High responsivity and speed are achieved by utilizing (1) increased absorption at low temperatures by proper doping concentrations, (2) an integrating sphere coupled to a conical light pipe, (3) suitable thermal conductance via the electrical leads to the heat sink clamp, and (4) cooled LWP filters, including a crystal-quartz field lens in the entrance aperture of the light pipe to limit the acceptance angle to 13° 44 . ́ An elaborated theory of bolometer performance is presented by means of which various parameters are correlated and evaluated. Load curves were obtained for heat sink temperatures of 1.55°K and 4.22°K, and 500°K blackbody responsivity measurements were made with λ ⩾ 142 μ. For the operating point of (3.22 V. 1.50 μA) at 1.65°K which yields the minimum NEP, the dynamic thermal conductance is 161 μW/°K, the effective emissivity is ϵ e = 0.512, the absorbed background radiant power is 6.52 μW, the effective thermal capacitance is C = 45.2 nJ/°K , and the ultimate responsivity (infinite load, unity emissivity) in the zero-frequency limit is R ∞(0) = −42.0 kV/ W. The response time constant for infinite load at the critical frequency f c = 604 Hz is τ τ∞ = 263 μ sec. The noise spectrum of the bolometer system connected to a sibeciallyconstructed FET pre-amplifier was measured and resolved into its various contributidns. The minimum NEP value achieved for the bolometer system under optimum operating conditions and pertaining to the recommended operating frequency range of f = 200–500 Hz, corrected to ϵ e = 1 and including the pre-amplifier noise contribution, is2.3 × 10 −12 W/√ Hz.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
