Photodiode with orthogonal layer structure
Embodiments provide a photodiode having two electrodes and an absorption volume for absorbing photons, wherein the absorption volume has a photon entry area, wherein the two electrodes are configured to generate an electric field in an active region between the two electrodes when a reverse voltage is applied, wherein the electric field runs parallel to the photon entry area, wherein, starting from a surface of a semiconductor substrate of the photodiode, the two electrodes essentially extend orthogonally to the surface in a depth direction of the semiconductor substrate, wherein the photodiode has at least one guard structure formed in the semiconductor substrate that is disposed below at least one of the at least two electrodes.
1 . A method for producing a photodiode, the method comprising:
providing a semiconductor substrate,
providing at least two electrodes in or on the semiconductor substrate, wherein, starting from a surface of the semiconductor substrate of the photodiode, the at least two electrodes essentially extend orthogonally to the surface in a depth direction of the semiconductor substrate,
providing a diode layer stack between the at least two electrodes, wherein layers of the diode layer stack essentially run orthogonally to the surface of the semiconductor substrate,
forming, in the semiconductor substrate, at least one guard structure below at least one of the at least two electrodes,
wherein the at least two electrodes, the at least one guard structure and the diode layer stack are provided in the semiconductor substrate by
forming, starting from the surface of the semiconductor substrate, at least two spaced-apart recesses in the semiconductor substrate,
forming a guard structure recess below one of the at least two electrodes,
doping the semiconductor substrate between the at least two spaced-apart recesses, starting from the at least two spaced-apart recesses and partially starting from the guard structure recess, to form the at least one guard structure and the diode layer stack between the at least two spaced-apart recesses, wherein the layers of the diode layer stack essentially run orthogonally to the surface of the semiconductor substrate,
providing the at least two electrodes in the at least two spaced-apart recesses.
2 . The method according to claim 1 ,
wherein the at least two spaced-apart recesses are formed by etching or by local oxidation of the semiconductor substrate and subsequent removal of oxide or by growing by selective deposition.
3 . The method according to claim 1 ,
wherein the semiconductor substrate is doped by means of coating with a dopant-comprising layer by chemical vapor deposition or by means of doping from a gas phase.
4 . The method according to claim 1 ,
wherein the at least two electrodes are provided on the semiconductor substrate, and
wherein the at least two electrodes and the diode layer stack are provided on the semiconductor substrate by
layer-by-layer growth of the at least two electrodes and
layer-by-layer growth and local doping of the diode layer stack.
5 . The method according to claim 3 ,
wherein the diode layer stack is doped by ion implantation using photolithography.
6 . The method according to claim 1 ,
wherein the diode layer stack comprises:
a p + -doped layer,
an intrinsic or a p-doped layer,
a p-doped layer, and
an n + -doped layer;
or wherein the diode layer stack comprises:
an n + -doped layer,
an intrinsic or an n-doped layer,
an n-doped layer, and
a p + -doped layer.
7 . The method according to claim 1 ,
wherein the at least two electrodes are formed by providing and structuring a metallization layer and/or heavily doped layer.
8 . The method according to claim 1 ,
wherein the photodiode is an avalanche photodiode or a photoelectron multiplier.