▎ 摘　　要

NOVELTY - The device has a substrate, where an epitaxial layer is arranged on the substrate. The epitaxial layer is set at specific interval with a source electrode and a drain electrode, where the source electrode and the drain electrode are provided with a grid electrode. The epitaxial layer is provided with a heat conducting piece located at two sides of the grid electrode. A side of the substrate away from the epitaxial layer is provided with a grounding metal layer. The active region of the device penetrates through the substrate and the epitaxial layer is provided with at least one heat conducting column. Two ends of the heat conducting column are connected with the grounding metal layer and the heat conducting piece. USE - High-electron-mobility transistor (HEMT) device e.g. heterojunction, field-effect transistor (FET). ADVANTAGE - The radiating effect of HEMT device can be improved by increasing the side radiation. The heat generated by the grid electrode can be timely conducted to the heat conducting piece, so as to improve the radiating effects of the HEMT device. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a preparation method for HEMT device. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the HEMT device. 10Invention application hemt device 310Source 320Drain electrode 330Gate 340Grounding back hole 410Heat conducting piece 420Heat conducting column