Dopant diffusion modulation in GaN buffer layers
AssigneeEfficient Power Conversion Corporation
InventorsRobert Beach, Guang Yuan Zhao
Life of this patent
Estimating the term…
Abstract
An enhancement mode gallium nitride (GaN) transistor with a Mg doped layer and a Mg growth interruption (diffusion barrier) layer to trap excess or residual Mg dopant. The Mg growth interruption (diffusion barrier) layer is formed by growing GaN, stopping the supply of gallium while maintaining a supply of ammonia or other nitrogen containing source to form a layer of magnesium nitride (MgN), and then resuming the flow of gallium to form a GaN layer to seal in the layer of MgN.
Claims11
An enhancement mode gallium nitride (GaN) transistor comprising:
- a substrate;
- a set of transition layers above the substrate;
- a doped layer of material comprising a first concentration of dopant atoms;
- a set of growth interrupt layers above the set of transition layers, wherein said growth interrupt layers contain dopant atoms in a modulated and decreasing concentration, wherein the dopant atoms are selected from the group consisting of magnesium, iron, nickel, manganese, calcium, vanadium, and other transition metals;
- and
- a buffer layer of material comprising gallium nitride formed above the set of growth interrupt layers.
A method of manufacturing an enhancement mode gallium nitride (GaN) transistor, the method comprising:
- forming a set of transition layers over a substrate;
- growing a material doped with magnesium (Mg) over the transition layers;
- starting a flow including a supply of gallium (Ga)-containing material and a supply of a nitrogen source to grow a GaN material over the Mg doped material;
- stopping the supply of Ga-containing material while maintaining the supply of nitrogen source to form an Mg doped nitride material;
- after forming the Mg doped nitride material, resuming the supply of Ga-containing material to form a GaN material over the Mg doped nitride material;
- and
- forming a buffer layer over the last-formed GaN material.
A method of manufacturing an enhancement mode gallium nitride (GaN) transistor, the method comprising:
- forming a set of transition layers over a substrate;
- growing a doped material comprising a first concentration of dopant atoms over the transition layers;
- providing a flow of nitrogen and Group III element containing gases;
- stopping flow of Group III element containing gases while maintaining a supply of nitrogen;
- reducing temperature after stopping flow of the Group III element containing gases;
- restarting flow of Group III element containing gases after reducing temperature;
- elevating temperature after restarting the flow of Group III element containing gases;
- and
- forming a buffer layer.
Dependencies are inferred from the claim text.