| 摘要 |
PURPOSE: To provide a resonant photo cavity which is resonant only with the desired wavelength by forming a sequence of a low refractive index and a high refractive index layer on a semiconductor structure. CONSTITUTION: A light detector structure 11 is composed of a semiconductor base board 12, absorption region 13, and electrodes 14, 15. On this board 12 a bottom dispersion type plug reflector mirror 17, active region 18, and upper dispersion type plug reflector mirror 19 are laminated one over another by means of electron beam evaporation process so that a micro-cavity 16 is formed. Mirrors 17, 19 consist of a plurality of layers in pairs having a thickness ofλ/4, and the layers belonging to the same pair are equipped with different refractive indices, high and low. The materials of different layers, their values of refractive index, and the number of pairs provided (period) should be selected previously, and each mirror is equipped with its desired reflection characteristics. The active region 18 with low refractive index contacting with the high refractive index layer should have a thickness ofλ/2. The incident beam of light to the over-layer part of the mirror 19 is passed through the cavity 16 to reach the base board 12 and passes through it, where the sensing efficiency is, for example 52% at a resonance wavelength of 1,350nm, and 4% response for non-resonant wavelengths.
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