论文标题
薄PB（111）膜中的量子孔和修改图像电位状态：局部工作函数的估计值
Quantum-well and modified image-potential states in thin Pb(111) films: an estimate for the local work function
论文作者
论文摘要
在SI（111）7 $ \ times $ 7的底物上生长的PB（111）膜上方的薄pb（111）膜中的量子限制的电子状态，例如薄PB（111）膜和修改的图像电位状态（IP）（IPS）。通过绘制$ n- $ th排放共振的位置$ u^{\，} _ n $ vess $ n^{2/3} $，并外应将线性拟合适用于依赖关系$ u^{\，} _ n（n^{2/3}）$在$ N = 0 $ n = 0 $ n = 0的情况下，我们估计，我们估算了p的n（n^{2/3}）$。 $ w \ simeq 3.8 \ pm 0.1 \，$ ev。我们在实验上证明，STM尖端形状的修改可以改变与相同PB露台的量化IPS水平相关的发射峰的数量；但是，它不会影响Flat PB露台的局部工作功能的估计。我们观察到，如果STM尖端变得更钝，则与QWS和修改后的IPS共振相关的差分隧穿电导$ di/du $的最大值$ di/du $也不明显。
Quantum-confined electronic states such as quantum-well states (QWS) inside thin Pb(111) films and modified image-potential states (IPS) above the Pb(111) films grown on Si(111)7$\times$7 substrate were studied by means of low-temperature scanning tunnelling microscopy (STM) and spectroscopy (STS) in the regime of constant current $I$. By plotting the position of the $n-$th emission resonances $U^{\,}_n$ versus $n^{2/3}$ and extrapolating the linear fit for the dependence $U^{\,}_n(n^{2/3})$ in the high-$n$ limit towards $n=0$, we estimate the local work function for the Pb(111) film: $W\simeq 3.8\pm 0.1\,$eV. We experimentally demonstrate that modifications of the shape of the STM tip can change the number of the emission peaks associated with the resonant tunnelling via quantized IPS levels for the same Pb terrace; however it does not affect the estimate of the local work function for the flat Pb terraces. We observe that the maxima in the spectra of the differential tunnelling conductance $dI/dU$ related to both the QWS and the modified IPS resonances are less pronounced if the STM tip becomes more blunt.
