Nitride semiconductor template and nitride semiconductor device
There is provided a method for manufacturing a nitride semiconductor template constituted by forming a nitride semiconductor layer on a substrate, comprising: (a) forming a first layer by epitaxially growing a nitride semiconductor containing aluminum on the substrate; (b) applying annealing to the first layer in an inert gas atmosphere; and (c) forming a second layer by epitaxially growing a nitride semiconductor containing aluminum on the first layer by a vapor phase growth after performing (b), and constituting the nitride semiconductor layer by the first layer and the second layer.
1. A nitride semiconductor template having a nitride semiconductor layer formed on a substrate,
the nitride semiconductor layer comprising:
a first layer formed on the substrate, made of nitride semiconductor containing aluminum, with a substrate-side surface being nitrogen polarity plane, and with a surface on a side opposing to the nitrogen polarity plane being a group-III polarity plane; and
a second layer formed on the group-III polarity plane of the first layer, and made of nitride semiconductor containing aluminum,
wherein the first layer and the second layer are distinguished depending on a difference of an impurity concentration,
an average dislocation density on a front surface of the first layer is 1×10 9 numbers/cm 2 or less,
an average dislocation density on a front surface of the second layer is 1×10 9 numbers/cm 2 or less, and
the substrate is a sapphire substrate or a silicon carbide substrate.
2. The nitride semiconductor template according to claim 1 , wherein
the first layer has a surface roughness RMS of the group-III polarity plane of 1 to 50 nm, and
the second layer has a surface roughness RMS of a front surface of 10 nm or less.
3. The nitride semiconductor template according to claim 1 , wherein the first layer and the second layer are made of aluminum nitride, indium aluminum nitride, aluminum gallium nitride, or aluminum gallium indium nitride which are represented by In 1-x-y Al x Ga y N (0≤x+y≤1, 0<x≤1, 0≤y≤1).
4. A nitride semiconductor device, comprising
the nitride semiconductor template of claim 1 , and
a nitride semiconductor lamination structure grown and formed on the nitride semiconductor template.