| 摘要 |
PURPOSE:To enable fast response by sequentially growing one conductivity type contact layer and one conductivity type optical absorption layer 3 on a substrate, and selectively removing both layers so that no n<+> region exists under the bonding pad, thereby reducing the capacitance. CONSTITUTION:On a Si-GaAs substrate 1, an n<+>-GaAs layer 2 as a contact layer and an n<->-GaAs layer 3 as an optical absorption layer are sequentially grown, selective etching is performed leaving the photo detecting portion of the layer 3, and selective etching is performed leaving the photo detecting portion of the layer 2 and the n-side bonding pad portion. Then, an n<->-Al0.3 Ga0.7As layer 4 as a high-resistance layer (window layer) is grown, and using as a mask a Si3N4 layer 6 formed on the surface of the layer 4 by etching, Zn is diffused to form a p<+> type region 5. A p-side ohmic electrode 8 containing the bonding pad therein and composed of Ti/Pt/Au is formed surrounding a photo detecting portion 7, and an n-side ohmic electrode 9 of AuGe/Au if formed on the layer 2. Since overlapping of the layer 2 and the electrode 8 is eliminated is both, unnecessary capacitance except for the photo detecting portion is reduced, enabling the capacitance of the whole pin diode to be reduced.
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