Temperature-Independent Switching Rates for a Random Telegraph Signal in a Silicon Metal-Oxide-Semiconductor Field-Effect Transistor at Low Temperatures
We have observed discrete random telegraph signals (RTS'S) in the drain voltages of three, observed above 30 K were thermally activated. The switching rate for the only RTS observed below 30 K was thermally activated above 30 K but temperature-independent below 10 K. To our knowledge, this cross-over from thermal activation to tunneling behavior has not been previously observed for RTS's Metal-oxide-semiconductor field-effect transistors (MCEWETS) often exhibit relatively large levels of low-frequency (1/fl noise) [1,2]. Much evidence suggests that this noise is related to the capture all cases, switching rates have been thermally activated, often with different activation energies for capture and/or emission is accompanied by lattice relaxation. Though thermally activated behavior has sufficiently low temperatures [7,9]. While not observed in MOSFETS, cross-over from thermal activation to configurational tunneling has been observed for RTS's in junctions [13]. drain voltage was observed to randomly switch between two discrete levels, designated as Vup and Vdn, similar to RTS's reported by others [2,7'- 11 ]. We have characterized six RTS `S for temperatures above 30 K where thermally activated switching rates are observed. The properties of five of these have been the trap, i.e., the mean time a captured charge carrier spends in the trap before it is emitted. Similarly, we identify the mean time in the low resistance state ( trup in state Vup) as the capture time rc. F@ure 1 shows a typical time trace of the drain-voltage fluctuation &d(t)= Vd(t)+Vd>. This indicate that both the mean capture and emission times become independent of Tat low temperatures and where a= capture or emission, is temperature independent. The solid curve in Figure 3(a) (mean capture time) was obtained using a weighted nonlinear charge carriers are not in thermal equilibrium with the lattice, i.e., that while the lattice is being cooled Instead, we believe that the transition from thermally activated to temperature-independent switching rates is associated with a lattice relaxation mechanism similar to that observed in metal- insulator-metal tunnel junctions [13]. Capture and emission of carriers are mediated by lattice relaxation, which proceeds via a thermally activated process at higher temperatures and a configurational tunneling electron capture rate depended on both lattice and electron temperatures while the emission rate Fkure 2. Arrhenius plot showing the thermally-activated behavior of both the mean capture (triangle) and emission (square) times of the RTS for temperatures above 20 K'.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sandia National Lab. (SNL-CA), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 9473
- Report Number(s):
- SAND99-1824J; TRN: AH200124%%274
- Journal Information:
- Applied Physics Letters, Other Information: Submitted to Applied Physics Letters; PBD: 19 Jul 1999
- Country of Publication:
- United States
- Language:
- English
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