Low doped layer for nitride-based semiconductor device
AssigneeVelox Semiconductor Corporation
InventorsMilan Pophristic, Michael Murphy, Richard A. Stall, Bryan S. Shelton, Linlin Liu, Alex D. Ceruzzi
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Abstract
A repeatable and uniform low doped layer is formed using modulation doping by forming alternating sub-layers of doped and undoped nitride semiconductor material atop another layer. A Schottky diode is formed of such a low doped nitride semiconductor layer disposed atop a much more highly doped nitride semiconductor layer. The resulting device has both a low on-resistance when the device is forward biased and a high breakdown voltage when the device is reverse biased.
Claims36
A method of forming a semiconductor layer structure, said method comprising:
- forming a doped nitride semiconductor layer by alternately growing doped nitride semiconductor material and initially undoped nitride semiconductor material repeatedly atop at least a portion of another layer in a manner that causes part of the dopants in the doped nitride semiconductor material to diffuse into the initially undoped nitride semiconductor material and results in the doped nitride semiconductor layer having a doping concentration that is substantially uniform along its depth and at most 2E16 cm−3.
A method of forming a Schottky diode, said method comprising:
- forming a doped nitride semiconductor layer by alternately growing doped nitride semiconductor material and initially undoped nitride semiconductor material repeatedly atop at least a portion of another layer in a manner that causes part of the dopants in the doped nitride semiconductor material to diffuse into the initially undoped nitride semiconductor material and results in the doped nitride semiconductor layer having a doping concentration that is substantially uniform along its depth and at most 2E16 cm−3;
- forming a metallic contact layer atop at least part of said doped nitride semiconductor layer to form a Schottky junction therewith;
- and
- forming at least one further metallic contact layer on at least part of said another layer in substantially ohmic contact therewith;
- whereby a ratio of an on-resistance of said Schottky diode to a breakdown voltage of said Schottky diode is at most 2×10−5 Ω cm2/V.
A method of forming a Schottky diode, said method comprising:
- forming a lower layer of n-type doped nitride semiconductor atop a substrate;
- forming an upper layer of n-type doped nitride semiconductor by alternately growing n-type doped nitride semiconductor material and initially undoped nitride semiconductor material repeatedly atop at least a portion of said lower layer of nitride semiconductor in a manner that causes part of the dopants in the doped nitride semiconductor material to diffuse into the initially undoped nitride semiconductor material and results in the upper layer of n-type doped nitride semiconductor having a doping concentration that is substantially uniform along its depth and at most 2E16 cm−3, said forming of said upper layer of n-type doped nitride semiconductor being carried out by a process selected from the group consisting of reactive sputtering, metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE) and atomic layer epitaxy, said lower layer of nitride semiconductor being more highly doped than said upper layer of nitride semiconductor;
- forming a first metal contact layer atop said upper layer of n-type doped nitride semiconductor such that a Schottky contact is formed;
- and
- forming a second metal contact layer atop said lower layer of n-type doped nitride semiconductor such that an ohmic contact is formed;
- whereby a ratio of an on-resistance of said Schottky diode to a breakdown voltage of said Schottky diode is at most 2×10−5 Ω cm2/V.
Dependencies are inferred from the claim text.