Abstract
We report on the noise figure, associated gain, and the current gain cutoff frequency for comparable 0.25-μm gate GaAs MESFET's and GaAs pseudomorphic HEMT's (p-HEMT's) as a function of cryogenic temperature. Contrary to previously published results which suggest that p-HEMT's should have a higher electron velocity and a lower noise figure than MESFET's due to the effects of the two-dimension electron gas (2-DEG), we have experimentally verified that this is not the case. We show clear evidence that the transport properties of the 2DEG in p-HEMT's do not make a significant contribution to the speed enhancement and noise reduction during high-frequency operation of these devices. It is the fundamental InGaAs material properties, specifically the Γ-L valley separation in the conduction band and associated effective mass of the electron in either GaAs or InGaAs channel, which limits the high-field electron velocity and thus the speed and noise performance of the devices.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 852-860 |
| Number of pages | 9 |
| Journal | IEEE Transactions on Electron Devices |
| Volume | 43 |
| Issue number | 6 |
| DOIs | |
| State | Published - 1996 |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering