Temperature-dependent single-electron tunneling effect in lightly and heavily doped GaN nanowires

We studied the electrical transport properties of GaN nanowires with two different doping levels. Measurements taken at various temperatures demonstrate that the electrical transport depends mainly on the single-electron tunneling effect up to a relatively high temperature of $\sim 150\mathrm{K}$. The aperiodic oscillations which we observed were attributed to single-electron tunneling through multiple quantum dots within the nanowire, which originated from various defects and the inhomogeneous distribution of the dopants.

Figure 1

The temperature-dependent $I\text{−}V$ curves of the heavily doped GaN nanowire. The temperatures were $235\mathrm{K}$, $78\mathrm{K}$, $19\mathrm{K}$, $10\mathrm{K}$, and $5.5\mathrm{K}$ from the above curve. The upper inset displays the semilog plot of resistances near zero-bias voltage. The lower inset shows the SEM image of the sample used in this study.

Figure 2

The temperature-dependent $I\text{−}V$ curves of the lightly doped GaN nanowire. The temperatures were $262\mathrm{K}$, $126\mathrm{K}$, $72\mathrm{K}$, and $5.3\mathrm{K}$ from the above curve. The upper inset shows the resistance as a function of inverse temperature $(1∕T)$. The lower inset shows the SEM image of the sample used in this study.

Figure 3

The temperature-dependent current change for the heavily doped GaN nanowire as a function of $V_g$ at several temperatures. The source-drain bias voltage was $4.25\text{mV}$. The gate bias varies from $+8\mathrm{V}$ to $-8\mathrm{V}$.

Figure 4

(a) The logarithmic plot of the temperature-dependent current change for the lightly doped GaN nanowire as a function of $V_g$ at several temperatures. The source-drain bias voltage was $30\text{mV}$. (b) $I–V_g$ curves as a function of $V$. The source-drain bias voltage varies from 0 to $+135\text{mV}$ with six voltage steps. The inset shows the $I\text{−}V$ curves as a function of $V_g=+10\mathrm{V}–-10\mathrm{V}$ with the five steps.