Low temperature growth and characterization of silicon delta doped GaInP/GaInAs/GaAs pseudomorphic heterostructures for use in high electron mobility transistors

Flow modulation organometallic vapor phase epitaxy (OMVPE) was used to synthesize selectively doped GaInP/GaInAs/GaAs pseudomorphic heterostructures. Transport properties of the two dimensional electron gas (2DEG) were optimized with various buffer formation schemes, techniques for single sided doping, and the channel and spacer layer thicknesses. GaAs buffers were deposited at 550°C and 635°C, while GaInP layers were grown at 550°C to promote atomic disordering. Achieving high 2DEG densities involved incorporating several delta doping supply layers separated by thin GaInP regions. Mobilities as high as 5100 cm² volt^-1 sec^-1 with associated 2DEG densities of 2.6×10¹² cm ^-2 were obtained at room temperature. Effects of vicinal substrates on mobilities was determined with conduction paths parallel and perpendicular to steps seen in AFM images. Finally, RF results are presented on devices with 0.25 μm×100 μm gate geometry