Electronic edge-state and space-charge phenomena in long GaN nanowires and nanoribbons

Abstract

We studied space-charge-distribution phenomena in planar GaN nanowires and nanoribbons (NRs). The results obtained at low voltages demonstrate that the electron concentration changes not only at the edges of the NR, but also in the middle part of the NR. The effect is stronger with decreasing NR width. Moreover, the spatial separation of the positive and negative charges results in electric-field patterns outside the NR. This remarkable feature of electrostatic fields outside the NR may be even stronger in 2D material structures. For larger voltages the space-charge-limited current (SCLC) effect determines the main mechanism of transport in the NR samples. The onset of the SCLC effect clearly correlates with the NR width. The results are confirmed by noise spectroscopy studies of the NR transport. We found that the noise increases with decreasing NR width and the shape of the spectra changes with voltage increase with a tendency toward slope (3/2), reflecting diffusion processes due to the SCLC effect. At higher voltages noise decreases as a result of changes in the scattering mechanisms. We suggest that the features of the electric current and noise found in the NRs are of general character and will have an impact on the development of NR-based devices.

Noise Spectroscopy of Transport and Ion‐Related Phenomena in Silicon Nanowire Field‐Effect Transistor Biosensors

“…Such behavior is characteristic of the SCLC effect in the nanowire channel. [ 12,15 ] Moreover noise spectra show features confirming SCLC regime formation as shown below. SCLC is characterized by its super linear dependence on the applied voltage V DS independent of the width of the sample, in accordance with the Mott–Gurney law: [ 16 ] $$\[ \begin{array}{*{20}{c}}{{I_{\rm{D}}} = \zeta \frac{{\varepsilon \mu V_{{\rm{DS}}}^2}}{{4\pi L}}}\end{array} \]$$where ζ is a coefficient of the order of unity, ε is the permittivity, μ is the mobility of free current carriers, and L is the length of the nanowire.…”

“…Such behavior is characteristic of the SCLC effect in the nanowire channel. [12,15] Moreover noise spectra show features confirming SCLC regime formation as shown below. SCLC is characterized by its super linear dependence on the applied voltage V DS independent of the width of the sample, in accordance with the Mott-Gurney law: [16]…”

Diffusion properties of electrons in GaN crystals subjected to electric and magnetic fields

“…For the calculation of components of the diffusion tensor, Dij, we used the following equation [27,39,40]: (6) where } , , {…”

“…The results of intensive investigations of wide-bandgap semiconductor compounds, in the particular, group-III nitrides, such as GaN, InN, AlN and related quantum heterostructures, can find various applications in the modern high-power and high-frequency microelectronics and optoelectronics [1,2]. The nitride compounds are discussed as perspective materials for new devices such as light-emitting diodes [3,4], optical switches [5], biosensors [6] and THz-active devices. The latter include electrically pumping THz sources [7][8][9], detectors [10] and modulators [5,11].…”

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“…The results of intensive investigations of wide-bandgap semiconductor compounds, in particular, group-III nitrides, such as GaN, InN, AlN and related quantum heterostructures, can find various applications in modern high-power and high-frequency microelectronics and optoelectronics [1,2]. The nitride compounds are discussed as perspective materials for new devices like to light-emitting diodes [3,4], optical switches [5], biosensors [6] and THz-active devices. The latter include electrically pumping THz sources [7][8][9], detectors [10] and modulators [5,11].…”