Effects of La content in ZrLaON gate dielectric on the interfacial and electrical properties of GaAs metal-oxide-semiconductor devices

GaAs MOS capacitors with ZrLaON as the high-k dielectric layer and LaON as the interfacial passivation layer (IPL) are fabricated and the effects of the La content in ZrLaON on the device performance are investigated. Experimental results show that ZrLaON with a moderate or high La content induces serious moisture absorption, thus deteriorating the interfacial and electrical properties of the device, even with the LaON IPL. By adjusting the La content to a suitable value, e.g. a La/(La Zr) atomic ratio of 13%, good interfacial and electrical properties can be obtained because the passivating role of La on the defects in ZrON can over-compensate the performance degradation induced by the moisture absorption. With the LaON IPL, further improvements in interfacial and electrical properties can be achieved because the LaON IPL can effectively passivate the As-O, Ga-O and As-As bonds at/near the high-k/GaAs interface.