Gallium nitride high electron mobility transistors (HEMTs) having reduced current collapse and power added efficiency enhancement
A High Electron Mobility Transistor structure having: a GaN buffer layer disposed on the substrate; a doped GaN layer disposed on, and in direct contact with, the buffer layer, such doped GaN layer being doped with more than one different dopants; an unintentionally doped (UID) GaN channel layer on, and in direct contact with, the doped GaN layer, such UID GaN channel layer having a 2DEG channel therein; a barrier layer on, and in direct contact with, the UID GaN channel layer. One of the dopants is beryllium and another one of the dopants is carbon.
1. A High Electron Mobility Transistor structure, comprising:
a substrate;
a high resistivity GaN buffer layer disposed on the substrate, the high resistivity GaN buffer layer doped with beryllium and having a resistivity greater than 2.2×10 3 ohm*cm;
a doped GaN thin film layer disposed on, and in direct contact with, the high resistivity GaN buffer layer, the doped GaN thin film layer having a thickness between 10 and 300 nm and having multiple different dopants where one of the dopants is beryllium and wherein the beryllium doping is 5×10 16 to 3×10 19 atoms/cm 3 and one of the dopants is carbon and wherein the carbon doping is less than the beryllium doping but higher than 1×10 16 atoms/cm 3 ; and
an unintentionally doped (UID) GaN channel layer on, and in direct contact with, the doped GaN thin film layer, the UID GaN channel layer having a 2DEG channel therein and wherein the UID GaN channel layer has a thickness between 50 and 200 nm.
2. The structure recited in claim 1 including a barrier layer on, and in direct contact with, the UID GaN channel layer.
3. The structure recited in claim 1 including a nucleation layer disposed on the substrate.
4. A High Electron Mobility Transistor structure, comprising:
a substrate;
a high resistivity GaN buffer layer disposed on the substrate, the high resistivity GaN buffer layer having a resistivity greater than 2.2×10 3 ohm*cm;
a doped GaN thin film layer disposed on, and in direct contact with, the high resistivity GaN buffer layer, the doped GaN thin film layer being doped with beryllium and carbon and wherein the beryllium doping is 5×10 16 to 3×10 19 atoms/cm 3 and wherein the carbon doping is less than the beryllium doping but higher than 1×10 16 atoms/cm 3 ; and
an unintentionally doped (UID) GaN channel layer on, and in direct contact with, the doped GaN thin film layer, the UID GaN channel layer having a 2DEG channel therein and wherein the UID GaN channel layer has a thickness less than 200 nm.
5. The structure recited in claim 4 wherein the UID GaN channel layer has a thickness between 50 and 200 nm.
6. The structure recited in claim 4 wherein the doped GaN thin film layer has a thickness of 10 to 300 nm.
7. The structure recited in claim 4 including a barrier layer on, and in direct contact with, the UID GaN channel layer.
8. A High Electron Mobility Transistor structure, comprising:
a substrate;
a high resistivity GaN buffer layer disposed on the substrate, the high resistivity GaN buffer layer doped with beryllium, iron and/or carbon;
a doped GaN thin film layer disposed on, and in direct contact with, the high resistivity GaN buffer layer, the doped GaN thin film layer being doped with beryllium and carbon and wherein the beryllium doping is 5×10 16 to 3×10 19 atoms/cm 3 and wherein the carbon doping is less than the beryllium doping but higher than 1×10 16 atoms/cm 3 ; and
an unintentionally doped (UID) GaN channel layer on, and in direct contact with, the doped GaN thin film layer, the UID GaN channel layer having a 2DEG channel therein and wherein the UID GaN channel layer has a thickness less than 200 nm.
9. The structure recited in claim 8 wherein the UID GaN channel layer has a thickness between 50 and 200 nm.
10. The structure recited in claim 8 wherein the doped GaN thin film layer has a thickness of 10 to 300 nm.