AlGaN/OaN　double　heterostructure　high　electron　mobility　transistor　(DH-HEMT＇s)　with　a　2.0μm　gate　length　and　a　4μm　channel　length　exhibiting　good　temperature　characteristics　has　been　demonstrated.　The　maximum　drain　current　Ids　and　extrinsic　transconductance　Gm　are　1300mA/mm　235mS/mm,　850mA/mm　174mS/mm　and　475mA/mm　95mS/mm,　respectively　at　T=-194°C,　20°C　and　400°C.　The　temperature　coefficient　of　I　ds　and　Gm　are　-1.4mA/°C　and　-0.24mS/°C　respectively.　©　2004　IEEE.