Higher operating temperature close to room temperature is an important direction for the development of third-generation infrared detectors.In this paper,the P-i-N ternary In1-xAlxSb thin film alloy material was epitaxially grown on InSb(100) substrate by MBE and verified bypreparedunit devices.The Al composition of the In1-xAlxSb film was conditioned and detected by RHEED oscillation and X-ray double crystal diffraction.5.3 μm thick thin film FWHM isabout 50 arcsec,Al componentsis about 1.9%.10 μm×10 μm atomic force surface roughness RMS is about 0.6 nm.The prepared unit device obtained the expected ideal effect and laid the foundation for the preparation of the next areafocal plane.