DEPLETION MODE SELECTIVE DOPED HETEROJUNCTION TRANSISTOR

Depletion Model Selective doped heterojunction transistor is designed and fabricated. Epitaxial modulation loping material were grown by a home-made MBE system. The gate length and width for low noise depletion devices were 1.2-1.5m and 2180m respecipely. The electron mobility of the material is typically 6500cm2/v.s at 300K and 75000 cm2/v.s at 77 K. The sheet electron concentration n, is 91011 cm-2. The transconductance of the depletion Mode levices is 100-130 ms/mm at room temperature. However at low temperature the transconductance is 200 ms/mm.Its noise figure is above 2-3dB.