P-N diode having a controlled heterostructure self-positioned on HgCdTe, for infrared imagers
AssigneeCommissariat A L'energie Atomique Et Aux Energies Alternatives
InventorsLaurent Mollard, Nicolas Baier, Johan Rothman
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Abstract
A device including at least one heterostructure p/n diode, including a substrate based on HgCdTe including for each diode: a first part having a first cadmium concentration; a concentrated part, having a second cadmium concentration, greater than the first concentration, forming a heterostructure with the first part; a p+ doped zone situated in the concentrated part and extending into the first part, forming a p/n junction with an n-doped position of the first part, or a base plate; and the concentrated part is only located in the p+ doped zone and forms a substantially constant cadmium concentration well.
Claims13
A device comprising at least one heterostructure p/n diode, comprising a substrate based on HgCdTe, mostly n-doped, the substrate comprising for each diode:
- a first part having a first cadmium concentration;
- a second part having a second cadmium concentration, greater than the first cadmium concentration, the second part, or concentrated part, forming a heterostructure with the first part;
- a p+ doped zone, or p doping zone, situated in the concentrated part and extending into the first part, and forming a p/n junction with an n-doped portion of the first part, or a base plate;
- wherein
- the concentrated part is only located in the p+ doped zone and forms a substantially constant cadmium concentration well.
A method for producing a device including at least one heterostructure p/n diode, comprising:
- a) ion implantation of an acceptor dopant in a substrate made of Hg1-xCdxTe, having a first cadmium concentration, comprising n type extrinsic donors, as a base plate;
- b) diffusion and activation of the dopant in the substrate, defining a p+ doped zone in the substrate;
- c) deposition of a passivation layer, wherein one of the elements is cadmium Cd, on top of the base plate and the p+ doped zone, prior to or following b);
- d) filling of mercury gaps initially present in the substrate or formed during the diffusing and activating the dopant, the base plate becoming n-doped and forming a p+/n junction, or p/n junction, with the p+ doped zone;
- and
- before d) and after b) and c), selective inter-diffusion of cadmium from the passivation layer into the p+ doped zone, forming a first part made of Hg1-xCdxTe, having a first cadmium concentration, and a second part made of Hg1-yCdyTe, or well or concentrated part, having a second cadmium concentration, which is substantially constant and greater than the first cadmium concentration, the well being located inside the p+ doped zone.
Dependencies are inferred from the claim text.