Molecular beam epitaxy growth and characterization of InGaP/InGaAs pseudomorphic high electron mobility transistors (HEMTs) having a channel layer over critical layer thickness

In/sub 0.5/Ga/sub 0.5/P/In/sub x/Ga/sub 1-x/As (x=0.33 and 0.40), pseudomorphic high electron mobility transistors (p-HEMTs) having a channel layer over the critical layer thickness were grown on patterned and nonpatterned GaAs substrates by using a compound-source molecular beam epitaxy (MBE). Characteristics of the highly strained InGaP/In/sub x/Ga/sub 1-x/As (x=0.33 and 0.40) p-HEMTs grown on patterned substrates were compared with those of conventional InGaP/In/sub 0.22/Ga/sub 0.78/As p-HEMTs grown on a nonpatterned substrate. The highly strained InGaP/In/sub 0.33/Ga/sub 0.67/As p-HEMT showed substantial improvements in device performances including DC (drain saturation current and transconductance), microwave (f/sub T/ and f/sub max/), low-frequency noise (Hooge parameter), and high-frequency noise (minimum noise figure and associated gain) characteristics compared with those of the conventional InGaP/In/sub 0.22/Ga/sub 0.78/As p-HEMT. The improvements in device performances of the highly strained InGaP/In/sub 0.33/Ga/sub 0.67/As p-HEMT are attributed to the improved transport property of the high-quality highly strained In/sub 0.33/Ga/sub 0.67/As channel layer achieved by the use of the patterned substrate growth. The results indicate the potential of highly strained InGaP/In/sub x/Ga/sub 1-x/As p-HEMTs having a channel layer in excess of the critical layer thickness grown on patterned GaAs substrates for use in high-performance microwave device applications.