Avalanche photodiode and method of making same
AssigneeRCA Corporation
InventorPaul P. Webb
Life of this patent
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Abstract
The invention is an improved avalanche photodiode having higher sensitivity at short wavelengths and a method of making it. The improvement comprises a contacting layer of varying thickness which can have a thin portion through which light enters the avalanche photodiode and a thicker portion surrounding the thin portion to which electrical contact can be made. This structure exhibits substantially greater sensitivity at wavelengths less than 500 nanometers without affecting the long wavelength sensitivity. The invention is also a method of forming the avalanche photodiode where the thicker portion and the thinner portions are sequentially formed using a two-step diffusion process.
Claims5
In an avalanche photodiode comprising:
- a semiconductor substrate having opposed major surfaces;
- a first layer in the substrate and adjoining a first major surface of the substrate;
- a second layer in the substrate spaced a distance from the first major surface and contiguous with a portion of the first layer;
- and
- a contacting layer in the substrate and adjoining a second major surface of the substrate through which light enters the photodiode;
- wherein the substrate, the second layer and the contacting layer are of one conductivity type and the first layer is of the opposite conductivity type thereby forming a p-n junction between the first and second layers;
- the improvement which comprises:
- the contacting layer being of varying thickness with the portion of the contacting layer through which light enters the photodiode being thinner than the remaining portion.
Dependencies are inferred from the claim text.