The influence of self-heating effects to hot-electron noise is investigated at 373 K and 293 K in nominally undoped AlGaN/GaN two-dimensional electron gas (2DEG) channels subjected to a strong pulsed electric field applied parallel to the heterointerface. The 2DEG channel was induced by spontaneous polarization and piezoelectric fields.

Hot-electron noise measurements were performed in the frequency band near 10 GHz where contributions due to generation-recombination noise and 1/f fluctuations were negligible. The gated modulation-type radiometric setup was used for investigation of the current fluctuations in the bias direction. The bias pulses ranging from 4 μ s to 0.5 μ s were chosen. At a high bias, the thermal quenching of hot-electron effects is observed. As a result, the associated kinetic processes (hot-electron sharing, for example) are shifted towards higher electric fields. In particular, the raise in lattice temperature shifts the onset field for the noise due to occupancy fluctuatio to appear.

In the delay-time dependent noise measurements, the decrease of the hot-electron noise temperature upon the delay time is observed when the bias pulse is on. To estimate the average lattice temperature, the microwave noise thermometry method [1,2] is applied. The lattice temperature was estimated through backward extrapolation of the delay-time dependent noise temperature T_n(t) measured after the voltage switch-off. The method is discussed and compared with other techniques.


1. M. de Murcia, E. Richard, J. M. Perraudin, A. Boyer, A. Benvenuti,
and J. Zimmermann, Semicond. Sci. Technol. 10, 515 (1995).

2. H. Hartnagel, R. Katilius, and A. Matulionis, Microwave Noise
in Semiconductor Devices, Wiley, New York, 2001,
p. 86-90.

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