Patent ID: 6831265
Filing Date: 2004-12-14
Classification: H01L

Abstract:
A photodetector having an optical absorption layer, said optical absorption layer having a bandgap Eg(eV), an absorption edge wavelength &lgr;e (&mgr;m) and an optical absorption coefficient provided by:Î±&af;(&varepsilon;&af;(Î»))=&it;Î±&af;(Î¾)=&it;0.18510-2&CenterDot;4.341060.0124&CenterDot;k&CenterDot;[Î¾(&LeftBracketingBar;Ai&af;(-Î¾)&RightBracketingBar;)2+&it;(&LeftBracketingBar;&dd;&dd;Î¾&it;Ai&af;(-Î¾)&RightBracketingBar;)]2,(A)wherein Ai&af;(-Î¾)=1Ï€&it;&Integral;0âˆž&it;cos&af;[13&it;t3+(-Î¾)&it;t]&it;&dd;t,Ai(âˆ’&xgr;) being an Airy function, &varepsilon;&af;(Î»)=E&af;(Î»)-Egk,&NewLine;&it;Eg=1.2398472447n&af;(Î»&it;â€ƒ&it;e)&CenterDot;Î»&it;â€ƒ&it;e,â€ƒ&it;E&af;(Î»)=1.2398472447n&af;(Î»)&CenterDot;Î»,&it;&NewLine;&it;n&af;(Î»)=1+[6432.8+2949810146-1Î»2+2554041-1Î»2]&CenterDot;10-8,(B)k=0.0124[Vd]23,(C)&egr;(&lgr;), n(&lgr;), E(&lgr;) being respectively a dielectric constant, a refractive index and a bandgap at the wavelength of an incident light, k being a coefficient obtained from a voltage V(V) applied to said optical absorption layer and a layer thickness d(m) of said optical absorption layer,wherein said thickness d(m) of said optical absorption layer is set with respect to said voltage V(V) applied to said optical absorption layer so as to satisfy a relationship: 106&lE;V/d&lE;107â€ƒâ€ƒ(D) wherein said photodetector includes a reflection region reflecting an incident light at a side of said optical absorption layer away from an optical surface to which a signal light is injected, said layer thickness d of said optical absorption layer being determined such that said optical absorption coefficient increases at a wavelength near 1.6 &mgr;m.