SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING A SEMICONDUCTOR DEVICE
A semiconductor device includes a first semiconductor layer formed on a substrate, a second semiconductor layer formed on the first semiconductor layer, a third semiconductor layer and a fourth semiconductor layer formed on the second semiconductor layer, a gate electrode formed on the third semiconductor layer, and a source electrode and a drain electrode contacting and formed on the fourth semiconductor layer, wherein the third semiconductor layer is formed of a semiconductor material for attaining p-type on an area just under the gate electrode, and a concentration of silicon in the fourth semiconductor layer is higher than that in the second semiconductor layer.
1 . A semiconductor device, comprising:
a first semiconductor layer formed on a substrate;
a second semiconductor layer formed on the first semiconductor layer;
a third semiconductor layer and a fourth semiconductor layer formed on the second semiconductor layer;
a gate electrode formed on the third semiconductor layer; and
a source electrode and a drain electrode contacting and formed on the fourth semiconductor layer,
wherein the third semiconductor layer is formed of a semiconductor material for attaining p-type on an area just under the gate electrode, and a concentration of silicon in the fourth semiconductor layer is higher than that in the second semiconductor layer.
2 . The semiconductor device as claimed in claim 1 , wherein the fourth semiconductor layer is doped with silicon at a concentration greater than or equal to 2×10 17 cm −3 and less than or equal to 1×10 19 cm −3 .
3 . The semiconductor device as claimed in claim 1 , wherein the first semiconductor layer is formed of a material including GaN.
4 . The semiconductor device as claimed in claim 1 , wherein the third semiconductor layer is of a material including GaN and doped with an impurity element for attaining p-type.
5 . The semiconductor device as claimed in claim 4 , wherein the impurity element for attaining p-type film is Mg.
6 . The semiconductor device as claimed in claim 1 , wherein the second semiconductor layer is formed of a material including AlGaN.
7 . The semiconductor device as claimed in claim 1 , wherein the fourth semiconductor layer is formed of a material including AlGaN or a material including InAlN or any combination thereof.
8 . The semiconductor device as claimed in claim 6 , wherein the fourth semiconductor layer is formed of a material including AlGaN and a composition ratio of Al in the second semiconductor layer is generally equal to a composition ratio of Al in the fourth semiconductor layer.
9 . The semiconductor device as claimed in claim 1 , wherein the substrate is a silicon substrate.
10 . The semiconductor device as claimed in claim 1 , wherein a buffer layer is formed of a material including AlGaN between the substrate and the first semiconductor layer.
11 . A power supply device comprising the semiconductor device as claimed in claim 1 .
12 . An amplifier comprising the semiconductor device as claimed in claim 1 .
13 . A method for manufacturing a semiconductor device, comprising:
laminating and forming a first semiconductor layer, a second semiconductor layer, and a third semiconductor layer on a substrate sequentially;
removing the third semiconductor layer in an area except an area for forming a gate electrode on the third semiconductor layer;
forming a fourth semiconductor layer on the second semiconductor layer with the third semiconductor layer being removed;
forming the gate electrode on the third semiconductor layer; and
forming a source electrode and a drain electrode to contact the fourth semiconductor layer,
wherein the third semiconductor layer is formed of a semiconductor material doped with an impurity element for attaining p-type and the fourth semiconductor layer is doped with silicon as an impurity element at time of forming thereof.
14 . The method for manufacturing a semiconductor device as claimed in claim 13 , wherein a concentration of silicon in the fourth semiconductor layer is higher than that in the second semiconductor layer.
15 . The method for manufacturing a semiconductor device as claimed in claim 13 , wherein the first semiconductor layer, the second semiconductor layer, the third semiconductor layer, and the fourth semiconductor layer are formed by an MOVPE.
16 . The method for manufacturing a semiconductor device as claimed in claim 13 , wherein a temperature of the substrate to form the fourth semiconductor layer is lower than a temperature of the substrate to form the second semiconductor layer.
17 . The method for manufacturing a semiconductor device as claimed in claim 13 , wherein the second semiconductor layer is formed of a material including AlGaN.
18 . The method for manufacturing a semiconductor device as claimed in claim 13 , wherein the fourth semiconductor layer is formed of material including AlGaN or a material including InAlN or any combination thereof.
19 . The method for manufacturing a semiconductor device as claimed in claim 13 , wherein silane is supplied to form the fourth semiconductor layer.
20 . The method for manufacturing a semiconductor device as claimed in claim 13 , wherein the first semiconductor layer is formed of a material including GaN.