Method of making avalanche photodiodes

Claim 1

A method of making avalanche photodiode segmented detectors with at least one active layer from an epitaxially grown heterostructure sample of GaAs l-x Sb x epitaxially grown on an Sn doped GaAs substrate comprising the steps of: (a) applying a photoresist solution to coat both sides of the sample; (b) exposing at a preselected wavelength, the sample's active layer through a first mask to open a plurality of windows on said sample; (c) etching the sample; (d) plating a conductive material over said plurality of windows on said active layer; (e) applying a layer of photoresist on the epilayer side of the sample; (f) exposing said epilayer side applied layer through a second mask at a preselected wavelength, said second mask having different dimensions than said first mask; (g) bombarding said epilayer side of said sample with protons to produce semi-insulating volumes on said epilayer side where photoresist does not cover said epilayer side surface; (h) removing said unexposed layer of photoresist such that no photoresist remains on the sample; (i) applying a layer of photoresist to coat both sides of the sample; (j) exposing the epilayer side of photoresist through a third mask at a preselected wavelength; (k) etching said sample; (l) depositing electrode contacts on the conductive material on said epilayer side of said sample; (m) plasma-etching away said undeveloped photoresist with O 2 ; (n) depositing ohmic contacts on preselected portions of the substrate side of said sample; (o) cleaving the edges of said sample to reduce leakage current; (p) mounting said sample; and (q) making electrical contacts to said deposited ohmic contacts and said deposited electrode contacts.

Claim 2

A method of making avalanche photodiode segmented detectors with at least one active layer from an epitaxially grown heterostructure sample of GaAs l-x Sb x epitaxially grown on an Sn doped GaAs substrate comprising the steps of: (a) applying a photoresist solution to coat both sides of the sample; (b) exposing at a preselected wavelength, the sample's active layer through a first mask to open a plurality of windows on said sample; (c) etching the sample; (d) plating a conductive material over said plurality of windows on said active layer; (e) applying a layer of photoresist on the epilayer side of the sample; (f) exposing said epilayer side applied layer through a second mask at a preselected wavelength, said second mask having different dimensions than said first mask; (g) bombarding said epilayer side of said sample with protons to produce semi-insulating volumes on said epilayer side where photoresist does not cover said epilayer side surface; (h) removing said unexposed layer of photoresist such that no photoresist remains on the sample; (i) applying a layer of photoresist to coat both sides of the sample; (j) exposing the epilayer side of photoresist through a third mask at a preselected wavelength; (k) etching said sample; (l) depositing electrode contacts on the conductive material on said epilayer side of said sample; (m) plasma-etching away said undeveloped photoresist with O 2 ; (n) depositing ohmic contacts on preselected portions of the substrate side of said sample; (o) cleaving the edges of said sample to reduce leakage current; (p) mounting said sample; and (q) making electrical contacts to said deposited ohmic contacts and said deposited electrode contacts.

Claim 8

A method of making avalanche photodiode segmented detectors comprising the steps of: (a) epitaxially growing several GaAs l-x Sb x layers on an Sn doped GaAs substrate, where x=the mole fraction of GaSb; (b) dip-pulling said substrate and layers in positive photoresist so as to coat both sides of the sample; (c) exposing said sample's outermost layer through a first mask, said exposure at a selected wavelength for a limited amount of time; (d) etching the sample in a solution of 1:1 HCl:H 2 O for one-to-two minutes; (e) plating palladium layers to form quadrants, said layer plated to a depth of 100-200 A; (f) dip-pulling a layer of photoresist on the sample to obtain a layer of photoresist approximately 4 μm thick; (g) exposing said layer of photoresist through a second mask at a selected wavelength for a limited amount of time, said second mask having different dimensions than said first mask; (h) bombarding the epitaxial layer side of said sample with protons to produce semi-insulating volumes around each quadrant; (i) dip-pulling a layer of photoresist on the sample; (j) etching said layer in 1:1 HCl:H 2 O solution for approximately one minute; (k) electroplating gold pad electrode contacts to each segment area where said developed photoresist has been removed; (l) plasma etching away said undeveloped photoresist with O 2 ; (m) sputtering Au-Ge, 12% Ge, 88% Au, ohmic contacts on selected areas of the substrate side of said sample; (n) cleaving the edges of said sample to reduce leakage current; and (o) mounting the sample.

Claim 9

A method of making avalanche photodiode segmented detectors comprising the steps of: (a) epitaxially growing several GaAs l-x Sb x layers on an Sn doped GaAs substrate, where x=the mole fraction of GaSb; (b) dip-pulling said substrate and layers in positive photoresist so as to coat both sides of the sample; (c) exposing said sample's outermost layer through a first mask, said exposure at a selected wavelength for a limited amount of time; (d) etching the sample in a solution of 1:1 HCl:H 2 O for one-to-two minutes; (e) plating palladium layers to form quadrants, said layer plated to a depth of 100-200 A; (f) dip-pulling a layer of photoresist on the sample to obtain a layer of photoresist approximately 4 μm thick; (g) exposing said layer of photoresist through a second mask at a selected wavelength for a limited amount of time, said second mask having different dimensions than said first mask; (h) bombarding the epitaxial layer side of said sample with protons to produce semi-insulating volumes around each quadrant; (i) dip-pulling a layer of photoresist on the sample; (j) etching said layer in 1:1 HCl:H 2 O solution for approximately one minute; (k) electroplating gold pad electrode contacts to each segment area where said developed photoresist has been removed; (l) plasma etching away said undeveloped photoresist with O 2 ; (m) sputtering Au-Ge, 12% Ge, 88% Au, ohmic contacts on selected areas of the substrate side of said sample; (n) cleaving the edges of said sample to reduce leakage current; and (o) mounting the sample.