DIAMOND ULTRAVIOLET SENSOR

• US 20090134403A1
• Filed: 11/22/2005
• Published: 05/28/2009
• Est. Priority Date: 11/25/2004
• Status: Active Grant

• Current Assignee: National Institute for Materials Science
• Original Assignee: National Institute for Materials Science
• Inventors: Liao, Meiyong, Koide, Yasuo, Jose, Antonio Alvarez
• Granted Patent: US 7,768,091 B2
• Time in Patent Office: Days
• US Class Current: 257/77
• CPC Class Codes: G01J 1/429 applied to measurement of ultraviolet light using counting tubes G01T
• CPC Class Codes: H01L 21/0435 Schottky electrodes
• CPC Class Codes: H01L 31/022408 for devices characterised by at least one potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/028 including, apart from doping material or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/09 Devices sensitive to infrared, visible or ultraviolet radiation H01L31/101 takes precedence
• CPC Class Codes: H01L 31/108 the potential barrier being of the Schottky type
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells

Abstract

In a conventional ultraviolet sensing device using a diamond semiconductor in a light-receiving unit, an Au-based electrode material is used for both a rectifier electrode and an ohmic electrode. However, the Au-based electrode material has fatal defects, such as poor adhesion to diamond, low mechanical strength, and furthermore poor thermal stability.

While avoiding complication of the device structure and exploiting the characteristics of a photoconductive sensing device, by using a carbide compound (TiC, ZrC, HfC, VC, NbC, TaC, CrC, MoC, and WC) of a high melting metal having a high mechanical strength for a rectifier electrode and/or a ohmic electrode, there is provided an extremely heat-stable diamond ultraviolet sensor having a light-receiving sensitivity to ultraviolet light having a wavelength of 260 nm or less.

Claims

1. A diamond ultraviolet sensor having a light-receiving sensitivity to ultraviolet light of a wavelength of 260 nm or less, which is a photoconductive type or a Schottky type light sensing device having two terminal electrodes to detect light irradiated to a light-receiving unit by the change in electrical resistance of a light-receiving unit material or the change in light induced current,

wherein a diamond surface, which is obtained by removing a surface conductive layer by an oxidation treatment of a hydrogen-terminated surface of a diamond semiconductor epitaxially grown on a diamond (100) or (111) plane single crystalline substrate which is formed by high-pressure synthesis, is used for bonding interfaces between the light-receiving unit and the electrodes,

a rectifier electrode is a single layer using no Au, and at least one selected from the group consisting of TiC, ZrC, HfC, VC, NbC, TaC, CrC, MoC, and WC, which is a carbide compound of a high melting point metal element, is used as the single layer, and

an ohmic electrode has a two-layered laminate structure using no Au, in which a single metal is used as a first layer which can form a solid solution with a carbide or carbon in the vicinity of a bonding interface between the diamond and the electrode by reaction with the diamond through a heat treatment, at least one selected from the group consisting of TiC, ZrC, HfC, VC, NbC, TaC, CrC, MoC, and WC, which is a carbide compound of a high melting point element, is used as a second layer, and the first layer and the second layer are processed by a heat treatment.

4. The diamond ultraviolet sensor according to any one of claims 1, 2, or 3, wherein the diamond surface from which the surface conductive layer is removed is a surface formed by an oxidation treatment performed for a hydrogen terminated diamond surface.

2. A diamond ultraviolet sensor which is a photoconductive type or a Schottky type light sensing device having two terminal electrodes to detect light irradiated to a light-receiving unit by the change in electrical resistance of a light-receiving unit material or the change in light induced current, wherein a diamond surface from which a surface conductive layer is removed is used for bonding interfaces between the light-receiving unit and the electrodes, and in at least one of the electrodes, an electrode layer in contact with the diamond surface is formed of at least one carbide compound of a high melting point metal element, which is selected from the group consisting of carbide of TiC, ZrC, HfC, VC, NbC, TaC, CrC, MoC, and WC.

3. A diamond ultraviolet sensor which is a photoconductive type or a Schottky type light sensing device having two terminal electrodes to detect light irradiated to a light-receiving unit by the change in electrical resistance of a light-receiving unit material or the change in light induced current, wherein a diamond surface from which a surface conductive layer is removed is used for bonding interfaces between the light-receiving unit and the electrodes, and at least one carbide compound of a high melting point metal element, which is selected from the group consisting of TiC, ZrC, HfC, VC, NbC, TaC, CrC, MoC, and WC, is used for a topmost layer portion of an ohmic electrode.