Semiconductor device and method for manufacturing the same
A semiconductor device and a method for manufacturing the same are provided. The semiconductor device includes a substrate, a channel layer on the substrate, a first barrier layer on the channel layer, a second barrier layer on the first barrier layer, and a gate element on the second barrier layer. The first barrier layer includes a first material with a first band gap, the second barrier layer includes a second material with a second band gap, and the first band gap is greater than the second band gap.
1 . A semiconductor device, comprising:
a substrate;
a channel layer on the substrate;
a first barrier layer on the channel layer;
a second barrier layer on the first barrier layer;
a gate element on the second barrier layer; and
a passive layer disposed conformally along a sidewall of the second barrier layer and an upper surface of the first barrier layer,
wherein the first barrier layer comprises a first material with a first band gap, the second barrier layer comprises a second material with a second band gap, and the first band gap is greater than the second band gap, the first barrier layer has a first aluminum content, the second barrier layer has a second aluminum content, and the first aluminum content is greater than the second aluminum content.
2 . The semiconductor device according to claim 1 , further comprising a control layer between the second barrier layer and the gate element, wherein the control layer comprises GaN doped with p-type dopants, and the channel layer comprises GaN.
3 . The semiconductor device according to claim 1 , wherein the first material includes AlN, GaN, InN, AlGaN, AlInN, GaInN or AlGaInN.
4 . The semiconductor device according to claim 1 , wherein the first material comprises Al a Ga 1−a N, the second material comprises Al b Ga 1−b N, and a is greater than b.
5 . The semiconductor device according to claim 4 , wherein a and b are constants.
6 . The semiconductor device according to claim 4 , wherein b linearly decreases from a bottom surface of the second barrier layer toward a direction away from the first barrier layer.
7 . The semiconductor device according to claim 4 , wherein b stepwise decreases from a bottom surface of the second barrier layer toward a direction away from the first barrier layer.
8 . The semiconductor device according to claim 4 , wherein a is greater than or equal to 0.20, and b is smaller than 0.20.
9 . The semiconductor device according to claim 4 , wherein a is greater than or equal to 0.18, and b is smaller than 0.18.
10 . The semiconductor device according to claim 1 , further comprising a dielectric layer on an upper surface of the passive layer, wherein the gate element directly contacts the dielectric layer and the passive layer.
11 . The semiconductor device according to claim 10 , further comprising a first source/drain element and a second source/drain element on opposite sides of the first barrier layer, wherein the first source/drain element and the second source/drain element directly contact the dielectric layer and the passive layer.
12 . The semiconductor device according to claim 10 , wherein the dielectric layer is on a sidewall of the gate element and a sidewall of the passive layer.
13 . The semiconductor device according to claim 1 , wherein the first barrier layer has a first thickness, the second barrier layer has a second thickness smaller than the first thickness.
14 . The semiconductor device according to claim 1 , further comprising a third barrier layer, wherein the second barrier layer is between the first barrier layer and the third barrier layer, the third barrier layer comprises a third material with a third band gap, and the third band gap is smaller than the first band gap.
15 . The semiconductor device according to claim 1 , wherein the second barrier layer partially covers the upper surface of the first barrier layer.
16 . The semiconductor device according to claim 1 , wherein the second material includes AlN, GaN, InN, AlGaN, AlInN, GaInN or AlGaInN.