Fabrication And Performance Study Of Ce:HfO₂ Ferroelectric Thin Film On In As/In_0.53Ga_0.47 As Substrate

Hafnium oxide(HfO₂)-based ferroelectric thin films have the characteristics of compatibility with complementary metal oxide semiconductor(CMOS)processes,strong feature size reduction capabilities and mature preparation processes.As a new type of ferroelectric material,HfO₂-based ferroelectric thin film has shown great potential in the application of ferroelectric memory and is expected to lead the development direction of new memory.Meanwhile,III-V semiconductors are explored as channels in metal oxide semiconducting(MOS)bulk devices due to their superior electron mobilities,which enable devices to be further scaled to achieve higher switching speeds and lower power consumptions.Combining the advantages of the two,the preparation of HfO₂-based ferroelectric memory with III-V semiconductor as the channel play an important role in promoting the high-density integration of ferroelectric memory.In this work,Ce-doped HfO₂(Ce:HfO₂)ferroelectric thin films are fabricated on In As/In_0.53Ga_0.47As III-V semiconductor substrates by chemical solution deposition(CSD).The effect of annealing process on the electrical properties and microstructure of Ce:HfO₂ ferroelectric thin films was investigated.The specific research content is as follows:(1)Preparation of Ce:HfO₂ ferroelectric thin film on heavily doped(100)In As substrate.The effect of annealing process on the surface morphology,phase structure and electrical properties of the films was investigated.The surface morphology of the film shows that the surface of the film is relatively flat and the root mean square(R_RMS)of the surface roughness is not greater than 1.1 nm.Ce exists in the HfO₂ film in the form of positive trivalent and positive tetravalent,which can induce the ferroelectric orthorhombic phase.Transmission electron microscopy and grazing incidence X-ray characterization confirm the existence of the ferroelectric orthorhombic phase in the film.In the piezoelectric test,the amplitude-voltage curve of the film is a butterfly curve and the phase-voltage curve indicates that the film can achieve a 180°phase reversal.Subsequently,the hysteresis loop and leakage current characteristic of the film under different annealing processes were tested.The film has the largest P_r value of 20?C/cm²when annealed in a N₂ atmosphere at 700?;while the film annealed in an O₂ atmosphere has a lower leakage current density.Endurance and retention tests show that the annealing process has little effect on the endurance properties and retention characteristics of the film.Under different annealing processes,the polarization of the films decreases less after 10⁸ times of cyclic electric field,and the films has good endurance properties.After being kept for more than 10⁴s,the polarization of the film hardly decreases,and the retention characteristics is good.(2)Preparation of Ce:HfO₂ ferroelectric thin film on heavily doped(100)In_0.53Ga_0.47As substrate.The effect of annealing process on the surface morphology,phase structure and electrical properties of the films was investigated.The surface morphology of the film shows that the film is relatively flat under various annealing conditions and the R_RMS is not greater than 1.1 nm.The film does not crystallize when annealed at 500?,but begin to crystallize at 550?.The existence of ferroelectric orthorhombic phase can be observed in each crystalline film.The film has the largest P_r value and lower leakage current density when annealed at 550?in N₂ atmosphere.Endurance and retention tests show that the annealing atmosphere has little effect on the endurance properties and retention characteristics of the film.Under different annealing atmospheres,the polarization of the films decreases less after 10⁸ times of cyclic electric field,and the films has good endurance properties.After being kept for more than 10⁴ s,the polarization of the film decreases less than 13%,and the film has good retention characteristics.