Monolithic integration of silicon CMOS and GaN transistors in a current mirror circuit
Schematic structure of a 100 mm diameter modified SOI wafer incorporating different silicon crystal structures and resistivities to address CMOS and GaN HEMT requirements. Windows are selectively etched down to the handle silicon (111) surface for growth of the GaN HEMT structure.
(Color online) Simulations for the effects on the dopant profiles for (a) boron P-type and (b) phosphorus N-type silicon implants following an MBE-like growth process (6.5 h at 750 °C) and an MOCVD-like process (2.5 h at 1000 °C).
(Color online) (a) Photograph of 100 mm SOI wafer with silicon CMOS following P-MBE GaN HEMT growth. The dark areas are single crystal nitride growth and the gray areas are polycrystalline nitride growth on top of the protective SiO2 for the CMOS. (b) Micrograph of GaN HEMT growth in irregular windows displaying good edge definition and no wire growth.
Microwave loss in dB/mm from 0.25 to 35 GHz for three transmission lines fabricated on a GaN HEMT in windows on a 100 mm modified SOI wafer containing silicon PMOS. The AlGaN surface layer was removed from the GaN HEMT.
Drain current in A/mm vs drain voltage for a 2 × 100 μm GaN HEMT device with a source-drain spacing of 3 μm and gate length of 0.25 μm. The family of curves is generated by stepping the gate voltage in 1 V increments from −4 to +2 V with the source grounded.
Microwave measurements at 10 GHz for a GaN HEMT device grown in windows on a modified SOI wafer with CMOS. The gate periphery is 10 × 125 μm. The drain voltage is 28 V with the source grounded. Output power, gain, and power added efficiency are measured as a function of input drive power.
Photomicrograph of part of a daisy chain interconnect test structure. The plated gold linewidth is 10 μm.
(Color online) (a) Photomicrograph of the current mirror integrated circuit, which incorporates three silicon PMOS transistors and four GaN transistors. The GaN current mirror network is 0.95 mm × 0.95 mm. (b) Current mirror performance displaying the drain current of the output GaN FET set by the output drain current of the PMOS circuit.
Microwave gain as a function of frequency for a GaN HEMT transistor at four PMOS drain currents.
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