A comprehensive reliability evaluation of high-performance AlGaN/GaN HEMTs for space applications

A systematic analysis of the reliability of GaN HEMT technologies for space applications in L-, S- and C- band up to 6 GHz (GH50, gate length 0,5 um) and C-, X- and Ku-band up to 20 GHz (GH25, gate length 0.25 um) has been carried out by means of on-wafer short-term (<24 h) tests, long-term high temperature storage and life tests. Specific long-term tests included: (1) 4000h thermal storage at three different temperatures (300°C, 325°C and 350°C); (2) 4000h DC life-test at 250°C, 300°C and 350°C junction temperature at a VDS value of 50 V and to 30 V respectively for GH50 and GH25 and at other bias points, up to VDS=100 V (GH50) and 60 V (GH25); (3) 500h RF life-tests at Tj=350°C, VDS=50V, IDS=50mA/mm, 1.7 GHz for GH50, and at Tj=325°C, VDS=30V, IDS=100mA/mm, 9 GHz for GH25, respectively. For both RF tests the input power corresponding to the maximum PAE value was selected. For all tested devices, degradation of main DC and RF parameters has been very limited. Even at 350°C, the highest temperature adopted for both thermal storage and life tests, the decrease of drain saturation current or transconductance did not exceed 20% after 4000 hours.