The influence of strong magnetic field on the 1/f noise in AlGaN/GaN metal‐oxide‐Semiconductor heterostructure field effect transistors (MOSHFETs) has been studied. The independence of 1/f noise on the magnetic fields up to 10 T where the strong geometric magneto‐resistance has been observed, shows that the carrier number fluctuations is the dominant mechanism of the noise in these devices. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The influence of strong magnetic field on the 1/f noise in AlGaN/GaN metal-oxide-Semiconductor heterostructure field effect transistors (MOSHFETs) has been studied. The independence of 1/f noise on the magnetic fields up to 10 T where the strong geometric magneto-resistance has been observed, shows that the carrier number fluctuations is the dominant mechanism of the noise in these devices. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The I-V characteristics of GaN/AlGaN HFET and 1/f noise at 4K have been measured in strong magnetic fields, where the electron mobility is affected by geometric magnetoresistance. The magnetic field dependence of the 1/f noise shows that the number of electrons fluctuations is the dominant mechanism of the 1/f noise and precludes the mobility fluctuations mechanism. The channel mobility extracted from the magnetoresistance data first increases with gate bias reaching the maximum value of similar to(0.9-1.0) m(2)/Vs at the 2D electron concentration of 5 x 10(12) cm(-2). This maximum value is close to the estimated ballistic mobility limit of 1.2 m(2)/Vs determined by the electron transit time with the Fermi velocity.

1 ∕ f noise in AlGaN∕GaN metal-oxide-semiconductor heterostructure field-effect transistors has been measured at 300K in strong magnetic fields up to 10T. The devices exhibited strong geometric magnetoresistance. The magnetic-field dependence of the 1∕f noise shows that fluctuations of the number of electrons is the dominant mechanism of the 1∕f noise.

We report on the results of the measurements of the low-frequency nitride/gallium aluminum nitride (GaN/GaAlN) heterojunctions grown on sapphire substrates. The noise spectra have the form of the 1/f noise with the Hooge parameter of approximately 10−2. The effects of band-to-band and impurity illumination on the low-frequency noise show that the nature of the 1/f noise in GaN might be a result of the occupancy fluctuations of the tail states near the band edges. This mechanism of the 1/f noise is similar to that in GaAs and Si.

The nature of 1/f noise, which appears in strongly doped n-type GaAs (electron density n0⋍1017 cm−3) under band-band illumination, has been investigated by measuring the low-frequency noise under high geometric magnetoresistance conditions. It is shown that such noise is of a volume nature and is due to carrier number (and not mobility) fluctuations. It is shown experimentally for the first time that surface noise can be distinguished from volume noise by performing measurements under high geometric magnetoresistance conditions.