Figure 4
Characteristics of device C, the Al–N-implanted TFET with a channel length of 80 nm. All of the measurements were conducted at 1.5 K unless otherwise noted. (a) ESR with a width of 4 MHz observed at (VD, VG) = (0.33 V, −0.36 V) in a magnetic field B// = 0.276 T (applied parallel to the source-to-drain current direction) and with P = −18 dBm. The ESR is similar to those obtained using other (VD, VG) sets, as in the case of device B. The g-factor was estimated to be 2.3, and consistent with device B for B//. A weak ESR with a g-factor of 2.7 was also observed (see the supplementary information). (b) Steady-state change in the drain current ΔID as a function of the pulse length of the pulse-modulated microwaves (simple pulse train with fixed pulse repetition of 1 μs). The microwave frequency was fixed at that necessary for ESR (∼9.01 GHz) with 2-μs pulse repetition. The plots are offset for clarity. The background current increase with increasing pulse length is due to the static shift in the effective VG caused by the microwave. (c) Oscillation frequency dependence on P. (d) Oscillation dependence on microwave detuning Δf at 1.5, 5, and 10 K. The microwave pulse repetition was 1 μs for all of the measurements, and P was −11, −13, and −10 dBm for the measurements at 1.5, 5, and 10 K, respectively. The characteristic Rabi amplitudes (at π-pulse) are 0.08 pA, 0.08 pA, and 0.04 pA and noise values are 0.01 pA, 0.01 pA, and 0.02 pA at 1.5 K, 5 K, and 10 K, respectively.
