Aluminumoxynitride (AlON) is investigated as a germanium oxide (GeO) desorption barrier layer for Ge MOSFETs. Interface and border traps in the AlON/GeO2/Ge gate-stack are discussed in detail and compared with those in the Al2O3/GeO2/Ge gate-stack via MOS and MOSFET structures. Although the interface traps remain the same for AlON and Al2O3 in the gate stacks, the AlON gate-stack exhibits a reduced border trap, which results in improved reliability over the Al2O3 gate-stack. This is supported by both the charge-trappingand low-frequency noise analyses.