Gallium nitride-based semiconductor device
A gallium nitride-based semiconductor device has a p-type layer that is a gallium nitride (GaN) compound semiconductor layer containing a p-type impurity and exhibiting p-type conduction. The p-type layer includes a top portion and an inner portion located under the top portion. The inner portion contains the p-type impurity and, in combination therewith, hydrogen. The top portion includes a region containing a Group III element and a Group V element at a non-stoichiometric atomic ratio.
1. A gallium nitride-based semiconductor device having a p-type layer that is a gallium nitride (GaN) compound semiconductor layer containing a p-type impurity and exhibiting p-type conduction, wherein the p-type layer comprises a top portion and an inner portion located under the top portion, wherein the inner portion contains the p-type impurity and, in combination therewith, hydrogen, wherein the inner portion has a hydrogen concentration of 1×10 18 cm −3 or more and an impurity concentration of 1×10 18 cm −3 to 1×10 21 cm −3 and wherein the top portion includes a region containing a Group III element and a Group V element at a non-stoichiometric atomic ratio, and wherein the top portion has a hydrogen concentration lower than that of the inner portion.
2. A gallium nitride-based semiconductor device according to claim 1 , wherein the inner portion of the p-type layer has a percent thickness of 40% to 99.9% with respect to a thickness of the p-type layer.
3. A gallium nitride-based semiconductor device according to claim 1 , wherein the inner portion has a hydrogen concentration that is equal to, or lower than, an impurity concentration.
4. A gallium nitride-based semiconductor device according to claim 1 , wherein the region containing a Group III element and a Group V element at a non-stoichiometric atomic ratio has a thickness of 1 to 10 nm from the top surface of the p-type layer in a depth direction.
5. A gallium nitride-based semiconductor device according to claim 1 , wherein the top portion of the p-type layer has a surface having Ga deposited thereon.
6. A gallium nitride-based semiconductor device according to claim 1 , wherein the p-type layer has a surface having joined thereto a gallium nitride semiconductor material containing a Group III element and a Group V element at a non-stoichiometric atomic ratio.
7. A gallium nitride-based semiconductor device according to claim 6 , wherein the gallium nitride semiconductor material is boron phosphide (BP) having a non-stoichiometric atomic ratio.