Nitride semiconductor substrate and method for manufacturing the same
AssigneeCoorsTek, Inc.
InventorsYoshihisa Abe, Masashi Kobata, Shintaro Miyamoto
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Abstract
A structure for increasing the concentration of two-dimensional electron gas without lowering mobility is provided. That is, a nitride semiconductor substrate is provided which includes a first layer, a second layer, and a third layer. The first layer has a composition of Ina1Alb1Gac1N (0≤a1≤1, 0≤b1≤1, 0≤c1≤1, a1+b1+c1=1). The second layer is formed on the first layer. The second layer has a composition of Ina2Alb2Gac2N (0≤a2≤1, 0≤b2≤1, 0≤c2≤1, a2+b2+c2=1) and has a band gap different from that of the first layer. The third layer is formed on the second layer and has a composition of AjB1-jN (A is a group 13 element, B is a group 13 element or a group 14 element, A≠B, 0<j<1).
Claims4
A nitride semiconductor substrate, comprising:
- a first layer having a composition of Ina1Alb1Gac1N (0≤a1≤1, 0≤b1≤1, 0≤c1≤1, a1+b1+c1=1);
- a second layer formed on the first layer, the second layer having a composition of Ina2Alb2Gac2N (0≤a2≤1, 0≤b2≤1, 0≤c2≤1, a2+b2+c2=1), the second layer having a band gap different from a band gap of the first layer;
- and
- a third layer formed on the second layer and having a composition of GajSi1-jN (0.3≤j≤0.6).
A method for manufacturing a nitride semiconductor substrate by metal organic chemical vapor deposition, in which the nitride semiconductor substrate includes a GaN electron transit layer as a first layer;
- an electron supply layer of Ina2Alb2Gac2N (a2=0, 0<b2≤1, 0≤c2<1, b2+c2=1) as a second layer;
- a GaN cap layer;
- and a GajSi1-jN (0.3≤j≤0.6) layer as a third layer, in this order,
- the method comprising:
- a first step of forming the second layer continuously on the first layer after the first layer is formed;
- a second step of forming the cap layer on the second layer after the first step;
- a third step of supplying a Ga source gas, a Si source gas, and an N source gas over a period of three seconds or less immediately after the completion of the second step to form the third layer;
- and
- a fourth step of stopping the supply of the Ga source gas and supplying the Si source gas and the N source gas after the third step.
Dependencies are inferred from the claim text.