Czochralski diffusional


InSb Photodiode Detectors and Arrays. Sensitive photodiodes (68,69) have been fabricated from single-crystal InSb using cadmium or zinc to form a -type region in bulk n-ty e material. High quahty InSb crystals can be grown by the infinite-melt process (70) where an InSb film is grown epitaxially (from the hquid phase) on a shce of InSb which was prepared in a conventional Czochralski vertical puller. The diode formation process typically is a closed-tube diffusion. Cleaned and etched samples of InSb ate placed in a quartz ampul with a limited amount of zinc or cadmium. After evacuation and sealing, the ampul is heated to ca 50°C below the crystal melting point. The metal vaporizes partially or completely, depending on the amount, volume of ampul, and temperature, and diffuses into the crystal after a few hours. The impurity-diffusion profile approximates the error-function law and the p—n junction is 1—5 p.m below the surface. Diode arrays (16) are formed by etching mesas ca 50 p.m square. Typical performance of InSb detectors is given in Table 1 and the spectral sensitivity is shown in Figure 9c. Up to 480 x 640 matrix arrays of InSb photodiodes in a mesa configuration have been demonstrated. Commercial units of 256 x 256 ate available. The mesa detector array is mated to a siUcon chip having an array of amplifiers and multiplex circuitry. Each diode is coimected to an amplifier input. The hybridization process consists of forming indium bumps on each diode mesa and on each amplifier input, using a photohthographic process and In evaporation and pressing the detector array chip to the siUcon integrated circuit chip. The infrared must pass through the InSb chip to reach the photodiode junction. To improve quantum efficiency the InSb is grown on GaAs or GaAsSb substrates as a thin layer. Quantum efficiency is greater than 50% for wavelengths greater than 2 p.m and less than the cutoff of InSb, 5.3 p.m. A protective coating (passivation) of the InSb photodiode for stable operation over several hours without frequent signal normalizations has not been found. However, infrared imaging cameras using hybrid InSb focal planes are a commercial reaUty. In a real-time imaging configuration the scene sensitivity is ca 0.04°C using an InSb infrared camera.  [c.432]


See pages that mention the term Czochralski diffusional : [c.903]   
Computational methods in surface and colloid science (2000) -- [ c.852 , c.895 , c.896 ]