Development of accurate on-wafer, cryogenic characterization techniques

Significant advances in the development of high electron mobility field-effect transistors (HEMT's) have resulted in cryogenic, low-noise amplifiers (LNA's) whose noise temperatures are within an order of magnitude of the quantum noise limit (h/spl nu//k). Further advances in HEMT technology at cryogenic temperatures may eventually lead to the replacement of maser and superconducting-insulator-superconducting (SIS) front-ends in the 1-100 GHz frequency band. Key to identification of the best HEMT's and optimization of cryogenic LNA's is accurate and repeatable device measurements at cryogenic temperatures. A cryogenic on-wafer noise and scattering parameter measurement system has been developed to provide a systematic investigation of HEMT noise characteristics. In addition, an improved parameter extraction technique has been developed to help understand the relationship between device structure and LNA performance.