# US 10,770,605 B2 · Photodiode with spinel oxide photoactive layer

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- Number: US 10,770,605 B2
- Document ID: US10770605B2
- Status: Granted
- Kind: B2
- Application number: 15/492,267
- Filed: 2017-04-20
- Published: 2018-10-25
- Granted: 2020-09-08
- Earliest claimed: 2017-04-20
- Assignees: King Abdulaziz University
- Applicants: King Abdulaziz University
- Inventors: Wageh Swelm; Fahrettin Yakuphanoglu; Ahmed A. Al-Ghamdi; Yusuf Abdulaziz Al-Turki
- Web page: https://patentgrep.com/patent/US10770605B2

## CPC

- H10F 77/1433: {Quantum dots}
- G01J 1/42: using electric radiation detectors (optical or mechanical part G01J1/04; by comparison with a reference light or electric value G01J1/10)
- G01J 5/0853: {having infrared absorbers other than the usual absorber layers deposited on infrared detectors like bolometers, wherein the heat propagation between the absorber and the detecting element occurs within a solid}
- G01J 5/28: using photoemissive or photovoltaic cells
- H10F 10/16: Photovoltaic cells having only PN heterojunction potential barriers
- H10F 30/222: the potential barrier being a PN heterojunction
- H10F 77/123: comprising only Group II-VI materials, e.g. CdS, ZnS or HgCdTe
- H10F 77/1437: {Quantum wires or nanorods}
- H10F 77/206: {for devices having potential barriers}
- H10F 77/211: {for photovoltaic cells}
- G01J 2001/4266: {for measuring solar light}
- Y02E 10/50: Photovoltaic [PV] energy
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A photodiode comprising a photoactive spinel oxide layer is described. This photoactive spinel oxide layer forms a contact with both a light absorption layer of quantum dots, quantum wires, or quantum rods, and an inorganic substrate layer. In some embodiments, the inorganic substrate layer and the photoactive spinel oxide layer form an isotype junction. Methods of characterizing the photodiode are provided and demonstrate commercially relevant electrical and optoelectronic properties, particularly the ability to operate as a photodetector with a high photosensitivity. An economical process for preparing the photodiode is provided as well as applications.

## Claims

### Claim 1

A photodiode, comprising:
an ohmic contact having a first work function;
an inorganic substrate layer in continuous contact with the ohmic contact;
a photoactive layer in continuous contact with the inorganic substrate layer;
a light absorption layer in continuous contact with the photoactive layer; and
a top electrode in contact with the light absorption layer, the top electrode having a second work function;
wherein the inorganic substrate layer comprises a semiconductor;
wherein the photoactive layer consists of ZnFe2O4 nanowires in N2, the ZnFe2O4 nanowires present at 80-90 vol % relative to a total volume of the photoactive layer;
wherein the ZnFe2O4 nanowires have widths of 35-45 nm and lengths of 170-350 nm;
wherein all ZnFe2O4 nanowires are physically adsorbed to the inorganic substrate layer and to the light absorption layer;
wherein the inorganic substrate layer and the photoactive layer are both p-type semiconductors forming an isotype junction between each other;
wherein the light absorption layer comprises at least one material selected from the group consisting of quantum dots, quantum rods, and quantum wires; and
wherein the second work function is higher than the first work function.

### Claim 2 (depends on 1)

The photodiode of claim 1, wherein the light absorption layer comprises quantum dots of at least one material selected from the group consisting of lead sulfide (PbS), lead selenide (PbSe), lead telluride (PbTe), cadmium selenide (CdSe), cadmium sulfide (CdS), and cadmium telluride (CdTe).

### Claim 3 (depends on 1)

The photodiode of claim 1, wherein the spinel metal oxide has a direct optical band gap of 2.0-3.0 eV.

### Claim 4 (depends on 1)

The photodiode of claim 1, wherein the semiconductor comprises at least one selected from the group consisting of silicon, germanium, indium gallium arsenide, lead (II) sulfide, indium phosphor, and mercury cadmium telluride.

### Claim 5 (depends on 1)

The photodiode of claim 1, wherein an optical band gap of the photoactive layer is greater than an optical band gap of the light absorption layer.

### Claim 6 (depends on 1)

The photodiode of claim 1, wherein the inorganic substrate layer has a thickness of 200-600 μm.

### Claim 7 (depends on 1)

The photodiode of claim 1, wherein the photoactive layer has a thickness of 20-250 nm.

### Claim 8 (depends on 1)

The photodiode of claim 1, wherein the light absorption layer has a thickness of 10-100 nm.

### Claim 9 (depends on 1)

The photodiode of claim 1, wherein the top electrode is aluminum.

### Claim 10 (depends on 1)

The photodiode of claim 1, wherein the inorganic substrate layer has a resistivity of 1-10 Ω·cm.

### Claim 11 (depends on 1)

The photodiode of claim 1, which has a barrier height of 0.5-1.25 eV.

### Claim 12 (depends on 1)

The photodiode of claim 1, which has a photoresponsivity of 0.10-0.40 A/W.

### Claim 13 (depends on 1)

The photodiode of claim 1, which has a photosensitivity defined as the ratio of illuminated current to dark current of 6000-7500 at a bias of 5.0-8.0 V.

### Claim 14 (depends on 1)

An electronic device comprising the photodiode of claim 1.

### Claim 15 (depends on 1)

A method for forming the photodiode of claim 1, the method comprising:
depositing the ohmic contact onto the inorganic substrate layer;
spin or drop coating the ZnFe2O4 nanowires onto the inorganic substrate layer, thereby forming the photoactive layer;
spin or drop coating at least one selected from the group consisting of quantum dots, quantum rods, and quantum wires onto the photoactive layer, thereby forming the light absorption layer;
depositing the top electrode onto the light absorption layer.

### Claim 16 (depends on 1)

A method of generating an electronic current, the method comprising:
irradiating the photodiode of claim 1 with a light source which has a wavelength of 150-1500 nm.