Patent ID: 7307291

Claim:
A GaN-based UV photo detector structure, comprising: a substrate made of a material selected from the group consisting of sapphire, 6H—SiC, 4H—SiC, Si, ZnO, GaAs, MgAl 2 O 4 , and an oxide monocrystalline having a lattice constant compatible with those of nitride semiconductors; an n-type contact layer having a thickness between 3000 Å and 40000 Å made of n-type doped Al a Ga b In 1−a−b N (0≦a,b≦1, a+b≦1) having a specific composition located on top of an upper side of said substrate; a light absorption layer having a thickness between 100 Å and 10000 Å made of undoped Al c Ga d In 1−c−d N (0≦c,d≦1, c+d≦1) having a band gap greater than 3.4 eV located on top of said n-type contact layer's upper surface; a negative electrode made of Ti/Al alloy located on top of a part of said n-type contact layer's upper surface; a light penetration layer having a wider band gap than that of said light absorption layer located on top of said light absorption layer comprising a superlattice structure formed by stacking a plurality of intermediate layers, each of said intermediate layers further comprising two base layers made of p-type doped Al e Ga f In 1−e−f N and Al g Ga h In 1−g−h N (0≦e,f,g,h≦1, e+f≦1, g+h≦1) respectively, and each of said base layers having a specific composition and a thickness between 50 Å and 200 Å, both independent of other base layers; a p-type contact layer having a thickness between 20 Å and 2000 Å made of p-type doped Al i Ga j In 1−i−j N (0≦i,j≦1, i+j≦1) having a specific composition located on top of said light penetration layer; a light penetration contact layer being one selected from the group consisting of a metallic conductive layer having a thickness between 20 Å and 200 Å, and a transparent oxide layer having a thickness between 200 Å and 3000 Å, located on top of a part of said p-type contact layer's upper surface; a positive electrode made of Ni/Au alloy located on top of another part of said p-type contact layer's upper surface not covered by said light penetration contact layer; and an anti-reflective coating layer made of one selected from the group consisting of SiO 2 , SiN 4 , TiO 2 , and a Distributed Bragg Reflector made of SiO 2 /TiO 2 located on top of said light penetration contact layer.