Improved 2DEG mobility in selectively doped GaAs/ N -AlGaAs grown by MOCVD using triethyl organometallic compounds

Abstract

In AlGaAs grown by MOCVD, carbon incorporation into the AlGaAs layer is discussed. For AlGaAs grown by trimethyl organometallic compounds, trimethyl aluminium and trimethyl gallium, remarkable carbon incorporation of up to about 1018 cm−3 is observed, although the carbon concentration decreases with the increase of the mole fraction ratio of arsine (AsH3) to III group organometallic compounds, [AsH3]/[III]. On the other hand, the use of triethyl organometallic compounds, triethyl aluminium and triethyl gallium, results in less carbon incorporation (∼1016 cm−3 independently of [AsH3]/[III]. Moreover, in selectively doped GaAs/n-Al0.3Ga0.7As heterostructures, two dimensional electron gas (2DEG) mobility is considerably improved using triethyl organometallic compounds in place of trimethyl organometallics. A 2DEG mobility of 445 000 cm2/V s is obtained for the SD heterostructure with a sheet electron concentration of 5.1 × 1011 cm−2 at 2 K.