Avalanche photodiode semiconductor structure having a high signal-to-noise ratio and method for manufacturing such a photodiode

摘要

A semiconductor structure, and method for manufacturing, of avalanche photodiode type for receiving electromagnetic radiation in a given wavelength range and including a first semiconductor area configured for absorption of the electromagnetic radiation, a second area configured for providing a multiplication of carriers, and a third semiconductor area in contact with the second semiconductor area. The second area includes at least two subparts with the second subpart configured to have a mean carrier multiplication rate that is more substantial than that of the first subpart.

主权项

1. An avalanche photodiode semiconductor structure for receiving an electromagnetic radiation in a given first wavelength range and comprising:
a first semiconductor area, of a first type of conductivity having a first face for receiving the electromagnetic radiation and a second face opposite the first face, the semiconductor material in which is formed the first semiconductor area having an energy band gap suitable for allowing absorption of the electromagnetic radiation, a second semiconductor area, in contact with the second face of the first semiconductor area, the second semiconductor area having a majority carrier concentration that is less than a carrier concentration of the first area, the second semiconductor area being suitable for providing a multiplication of carriers by impact ionisation that is preponderant for one type of carrier, a third semiconductor area, in contact with the second semiconductor area, the third semiconductor area being of a second type of conductivity opposite the first type of conductivity and having a majority carrier concentration that is greater than the majority carrier concentration of the second semiconductor area, the second semiconductor area comprises at least two subparts, a first subpart through which the second semiconductor area is in contact with the first semiconductor area and a second subpart connecting the first subpart to the third semiconductor area, the second subpart being suitable for having a mean carrier multiplication rate by micrometer that is greater than the mean carrier multiplication rate of the first subpart, wherein the second subpart is made from a semiconductor material having an energy band gap that is less than energy band gap of the semiconductor material in which is formed the first subpart to have the mean carrier multiplication rate by micrometer greater than that of the first subpart, wherein the first and the second subpart are made from mercury-cadmium tellurides of CdxHg1-xTe type with proportions x in cadmium that are different from one another, and wherein the first and the second subpart of the first semiconductor area are both layers of which the minimum thickness is greater than 200 nm.