Group III nitride based high electron mobility transistors

A semiconductor device prepared by a process comprising:

• providing a silicon-on-insulator (SOI) substrate, wherein the SOI substrate comprises a bulk Si(111) handle substrate;
• depositing a high pressure group (III)-nitride layer at a pressure in a range of about 200 Torr to about 400 Torr;
• depositing a low pressure group (III)-nitride layer deposited at a pressure in a range of about 150 Torr to about 190 Torr directly adjacent to the high pressure group (III)-nitride layer, the high pressure group (III)-nitride layer and the low pressure group (III)-nitride layer forming a compositionally homogeneous group (III)-nitride layer;
• locating a metal-group (III)-nitride layer between the substrate and the compositionally homogeneous group (III)-nitride layer;
• locating a metal nitride layer located between the substrate and the metal-group (III)-nitride layer, comprising a low-temperature metal-nitride layer deposited at a temperature in a range of about 900° C. to about 1000° C. and having a thickness in a range of 30 nm to 50 nm, and a high temperature metal-nitride layer directly adjacent to the low-temperature metal-nitride layer, deposited at a temperature in a range of about 1050° C. to about 1075° C. and having a thickness greater than 300 nm;
• wherein the compositionally homogeneous group (III)-nitride layer has a thickness dimension greater than a thickness dimension of a combination of the metal-nitride layer and the metal-group (III)-nitride layer;
• and
• wherein the high pressure group (III)-nitride layer of the compositionally homogeneous group (III)-nitride layer is directly adjacent the metal-group (III)-nitride layer.