Nitride semiconductor device including a horizontal switching device

A nitride semiconductor device comprising

• a horizontal switching device including:
• a substrate that is formed of a semi-insulator or a semiconductor;
• a channel forming layer that includes a first nitride semiconductor layer disposed above the substrate and a hetero-junction structure disposed above the first nitride semiconductor layer, the first nitride semiconductor layer providing an electron transit layer, the hetero-junction structure including at least one second nitride semiconductor layer and at least one third nitride semiconductor layer, the at least one second nitride semiconductor layer having a forbidden band width greater than the first nitride semiconductor layer and providing an electron donor portion, and the at least one third nitride semiconductor layer having a forbidden band width less than the at least one second nitride semiconductor layer;
• a source region and a drain region that are arranged apart from each other in one direction along a plane of the substrate, the source region and the drain region extending from a surface of the channel forming layer and reaching the first nitride semiconductor layer;
• and
• a gate region that is formed of a p-type semiconductor layer and is arranged between the source region and the drain region,
• the horizontal switching device being configured to generate a current between the source region and the drain region by a 2-dimensional electron gas carrier and a 2-dimensional hole gas carrier, the 2-dimensional electron gas carrier being induced in the first nitride semiconductor layer adjacent to an interface between the first nitride semiconductor layer and the at least one second nitride semiconductor layer, and the 2-dimensional hole gas carrier being induced between the at least one second nitride semiconductor layer and the at least one third nitride semiconductor layer positioned above the at least one second nitride semiconductor layer, wherein
• the gate region is divided into multiple parts stacked behind apart from each other in a perpendicular direction along the plane of the substrate, the perpendicular direction being perpendicular to a horizontal direction in which the source region and the drain region are arranged, the perpendicular direction further being perpendicular to a stack direction in which the first nitride semiconductor layer and the hetero-junction structure of the channel forming layer are stacked.