Al_(1-x)Sc_(x)Sb_(y)N_(1-y):An opportunity for ferroelectric semiconductor field effect transistor

For the in-memory computation architecture,a ferroelectric semiconductor field-effect transistor(FeSFET)incorporates ferroelectric material into the FET channel to realize logic and memory in a single device.The emerging groupⅢnitride material Al_(1-x)Sc_(x)N provides an excellent platform to explore FeSFET,as this material has significant electric polarization,ferroelectric switching,and high carrier mobility.However,steps need to be taken to reduce the large band gap of~5 eV of Al_(1-x)Sc_(x)N to improve its transport property for in-memory logic applications.By state-of-the-art first principles analysis,here we predict that alloying a relatively small amount(less than~5%)of Sb impurities into Al_(1-x)Sc_(x)N very effectively reduces the band gap while maintaining excellent ferroelectricity.We show that the co-doped Sb and Sc act cooperatively to give a significant band bowing leading to a small band gap of~1.76 eV and a large polarization parameter~0.87 C/m^(2),in the quaternary Al_(1-x)Sc_(x)Sb_(y)N_(1-y)compounds.The Sb impurity states become more continuous as a result of interactions with Sc and can be used for impurity-mediated transport.Based on the Landau-Khalatnikov model,the Landau parameters and the corresponding ferroelectric hysteresis loops are obtained for the quaternary compounds.These findings indicate that Al_(1-x)Sc_(x)Sb_(y)N_(1-y)is an excellent candidate as the channel material of FeSFET.