Semiconductor radiation detector and method of manufacturing same

Claim 2

A radiation detector comprising a semi-conductor body having two oppositely located major surfaces which are opposed to each other, a surface layer of a first conductivity type adjoining a first of said major surfaces, said surface layer in the semiconductOr body adjoining a substantially intrinsic intermediate region which extends through the semiconductor body to substantially the second major surface, an annular surface region of the second conductivity type being present at the second major surface, the first major surface comprising two substantially concentric grooves extending into the semiconductor body from the first major surface to a depth which is larger than the thickness of the surface layer of the first conductivity type, the grooves having unequal depths, a first one of said grooves terminating in the substantially intrinsic intermediate region, the second one of said grooves being deeper and extending through the substantially intrinsic intermediate region to the annular surface region of the second conductivity type, said annular region extending between the lower side of the second deeper groove and the second major surface.

Claim 3

A radiation detector as claimed in claim 1, characterized in that viewed on the first major surface the deeper second groove is situated within and is surrounded by the first shallower groove, a second annular surface region of the second conductivity type which extends at least partly between the lower side of the first groove and the second major surface and which is separated from the first groove by the substantially intrinsic intermediate region being present at the second major surface in addition to the already mentioned first annular surface region of the second conductivity type.

Claim 4

A radiation detector as claimed in claim 2, characterized in that a recess is present at the second major surface, in which both the part of the substantially intrinsic intermediate region extending mainly within the second deeper groove and the part of the intermediate layer present mainly outside said groove extend within the area of the recess substantially down to the second major surface, said parts being separated from each other at said major surface by the annular surface region of the second conductivity type present between the lower side of the second groove and the second major surface, the second annular surface region of the second conductivity type also partly adjoining the second major surface within the area of the recess.

Claim 5

A radiation detector as claimed in claim 3, characterized in that the edge of the recess adjoins in its entirely and exclusively the second annular surface region of the second conductivity type.

Claim 6

A method of manufacturing a radiation detector as claimed in claim 1, characterized in that a surface layer of the first conductivity type is provided at a first major surface of a semiconductor body of the second conductivity type, that two substantially concentric grooves of unequal depths are provided from the first major surface in the semiconductor body and extend at least through the surface layer of the first conductivity type, a substantially intrinsic intermediate region being formed by drifting of impurities provided in the surface layer under the influence of an electric field from said surface layer in the adjoining part of the semiconductor body, said formation of the substantially intrinsic intermediate region being at least once interrupted to provide at least the first shallow groove, the depth of the first groove being chosen to be so that the lower side of said groove remains entirely within the already formed part of the substantially intrinsic intermediate region and that the formation of the substantially intrinsic intermediate region is then continued until the formed substantially intrinsic intermediate region extends substantially down to the second oppositely located major surface of the semiconductor body.

Claim 7

A method as claimed in claim 5, characterized in that starting material is a monocrystalline p-type semi-conductor body of a material belonging to the group formed by germanium, silicon and cadmium telluride, the n-type surface layer and the substantially intrinsic intermediate region being formed by diffusion and driFt of lithium.

Claim 8

A method as claimed in claim 5, characterized in that the two grooves of unequal depths are provided during the same interruption of the formation of the substantially intrinsic intermediate region, the deeper groove being formed entirely through the already formed part of the intrinsic intermediate region and down to in the still remaining p-type part of the semiconductor body.

Claim 9

A method as claimed in claim 5, characterized in that the inner of the two substantially concentric grooves is provided to have a greater depth than the outer of said grooves and that a recess is provided at the second major surface after the formation of the substantially intrinsic intermediate region, which recess is so large that the part of the substantially intrinsic intermediate region extending mainly within the inner deeper groove, the part of the intermediate region present outside said inner groove, an inner annular surface region of the second conductivity type present between the deeper groove and the second major surface and separating said parts of the substantially intrinsic intermediate region from each other, and a part of a second outer annular surface region of the second conductivity type adjoin the second major surface within the edge of said recess.