MOCVD Growth of High Quality InGaAs HEMT Layers on Large Scale Si Wafers for Heterogeneous Integration With Si CMOS

Abstract

We report on the growth of In0.30Ga0.70As channel high electron mobility transistor (HEMT) epi-layers on a 200-mm Si substrate by metal-organic-chemical-vapor-deposition. The HEMT layers were grown on the Si substrate by using a ~3- ${\mu }\text{m}$ thick epitaxial buffer composing of a Ge layer, a GaAs layer, and a compositionally graded and strain relaxed InAlAs layer. The optimized epitaxy has a threading dislocation density of less than $2 {\times } 10^{{7}}$ cm−2 and a root mean square surface roughness of ~6.7 nm. The device active layers include a ${ {\delta } }$ -doped InAlAs bottom barrier, a ~15-nm thick InGaAs channel, a ~8-nm InGaP top barrier layer and a heavily doped InGaAs contact layer. MOSHEMTs with channel length down to 130 nm were fabricated. The devices achieve a peak transconductance of ${\sim }450 ~{\mu }\text{S}/ {\mu }\text{m}$ at ${V} _{ D}$ of 0.5 V. The peak effective mobility ( ${\mu }_{\text {eff}}$ ) in a device with a channel length of 20 $ {\mu }\text{m}$ device channel was ~3700 cm2/ $\text{V} {\cdot }\text{s}$ .