Studies of the DC, low-frequency, and microwave characteristics of uniform and step-doped GaAs/AlGaAs HEMTs

• Published in: IEEE transactions on electron devices 1989-10, Vol.36 (10), p.2288-2298
• Main Authors: Chau, H.-F., Pavlidis, D., Cazaux, J.-L., Graffeuil, J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Automatic testing; Cutoff frequency; Electron mobility; Electronics; Etching; Exact sciences and technology; HEMTs; Low-frequency noise; MODFETs; Predictive models; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Threshold voltage; Transistors; Voltage control
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/16.40913

A theoretical and experimental study of step-doped HEMTs (high electron mobility transition) with lightly and heavily doped regions is presented. Threshold voltage control and sensitivity with respect to growth parameters and recessing etching, as well as design criteria, are investigated for these structures. A three-regime charge control model is used to predict their performance. Using the same semianalytical theory, which was validated with the help of a self-consistent analysis, both conventional and step-doped HEMTs with an i-layer are compared. 1- mu m gate-length n-channel HEMTs with step-doped profile thicknesses of 25, 50, and 100 AA were fabricated and tested at low and high frequencies. The low-frequency noise can be controlled by the step thickness, and a noise analysis is presented. Cutoff frequencies of 16 to 18 GHz and maximum oscillation frequencies of 41 to 59 GHz were measured and correlated to the step thickness.< >