Nitride semiconductor substrate
View Patent ↗A nitride semiconductor substrate suitable for a high withstand voltage power device is provided in which current collapse is controlled, while reducing leakage current. In a nitride semiconductor substrate, wherein a buffer layer, an active layer, and an electron supply layer, each comprising a group 13 nitride, are stacked one by one on a silicon single crystal substrate, the buffer layer has a structure where a multilayer stack in which a pair of nitride layers having different concentrations of Al or Ga are repeatedly deposited a plurality of times on an initial layer of Al x Ga 1−x N (0≦x≦1) is stacked, and includes a doping layer whose carbon concentration is 1×10 18 to 1×10 21 cm −3 and whose Si concentration is 1×10 17 to 1×10 20 cm −3 , a thickness of the doping layer is 15% or more of the total thickness of the buffer layer.
1. A nitride semiconductor substrate, wherein a buffer layer, an active layer, and an electron supply layer, each comprising a group 13 nitride, are stacked one by one on a silicon single crystal substrate,
said buffer layer has a structure comprising a multilayer stack in which a pair of nitride layers having different concentrations of AI or Ga are repeatedly deposited a plurality of times on an initial layer of Al x Ga 1−x N (0≦×≦1),
said buffer layer further comprises a doping layer whose carbon concentration is 1×10 18 to 1×10 21 cm −3 and whose Si concentration is 1×10 17 to 1×10 20 cm −3 , and
a thickness of said doping layer is 15% or more of the total thickness of said buffer layer.
2. A nitride semiconductor substrate as claimed in claim 1 , wherein said doping layer has a multilayer structure in which a pair of nitride layers having different concentrations of Al or Ga are repeatedly deposited a plurality of times.
3. A nitride semiconductor substrate, wherein a buffer layer, an active layer, and an electron supply layer, each comprising a group 13 nitride, are stacked one by one on a silicon single crystal substrate,
said buffer layer has a structure comprising a multilayer stack in which a pair of nitride layers having different concentrations of Al or Ga are repeatedly deposited a plurality of times on an initial layer of Al x Ga 1−x N (0≦×≦1), and further comprises a doping layer whose carbon concentration is 1×10 18 to 1 × 10 21 cm −3 and whose Si concentration is 1×10 17 to 1×10 20 cm −3 ,
a thickness of said doping layer is 15% or more of the total thickness of said buffer layer, and
an oxygen concentration in said buffer layer is 5×10 17 to 5×10 18 cm −3 .
4. A nitride semiconductor substrate, wherein a buffer layer, an active layer, and an electron supply layer, each comprising a group 13 nitride, are stacked one by one on a silicon single crystal substrate,
said buffer layer has a structure comprising a multilayer stack in which a pair of nitride layers having different concentrations of Al or Ga are repeatedly deposited a plurality of times on an initial layer of Al x Ga 1−x N (0≦×≦1), and further comprises a doping layer whose carbon concentration is 1×10 18 to 1×10 21 cm −3 and whose Si concentration is 1×10 17 to 1×10 20 cm −3 ,
said doping layer has a multilayer structure in which a pair of nitride layers having different concentrations of Al or Ga are repeatedly deposited a plurality of times,
a thickness of said doping layer is 15% or more of the total thickness of said buffer layer, and
an oxygen concentration in said buffer layer is 5×10 17 to 5×10 18 cm −3 .