Donor deactivation in silicon nanostructures
Donor deactivation in silicon nanostructures
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DOI：
10.1038/nnano.2008.400
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发表时间：
2009-02-01
影响因子：
38.3
通讯作者：
Riess, Walter
中科院分区：
文献类型：
--
作者：
Bjork, Mikael T.;Schmid, Heinz;Riess, Walter
电子器件的工作依赖于半导体中可用的自由电荷载流子的密度;在大多数半导体器件中，该密度通过添加掺杂原子来控制。随着尺寸缩小以实现经济和性能效益，与半导体相邻的界面和材料的存在将变得更加重要，并最终完全决定器件的电子特性。为了维持性能的进一步改进，已经提出了新颖的场效应晶体管架构，例如FinFET（1，2）和纳米线场效应晶体管（3-7），作为当今使用的平面器件的替代品，并且还用于生物传感（8-10）和发电（11）中的应用。这种器件的成功操作将取决于我们在制造过程中精确控制主体半导体中活性杂质原子的位置和数量的能力。在这里，我们证明了半导体纳米线中的自由载流子密度取决于纳米线的尺寸。通过测量掺杂硅纳米线的电导率作为纳米线半径、温度和电介质环境的函数，我们表明施主电离能随着纳米线半径的减小而增加，并且它深刻地改变了可达到的自由载流子密度，其半径值远大于量子效应（12，13）和掺杂剂表面偏析效应（14）的值。在15 nm的纳米线半径处，由于导电沟道与其周围环境之间的介电失配（15），载流子密度已经比体硅中低50%。
The operation of electronic devices relies on the density of free charge carriers available in the semiconductor; in most semiconductor devices this density is controlled by the addition of doping atoms. As dimensions are scaled down to achieve economic and performance benefits, the presence of interfaces and materials adjacent to the semiconductor will become more important and will eventually completely determine the electronic properties of the device. To sustain further improvements in performance, novel field-effect transistor architectures, such as FinFETs(1,2) and nanowire field-effect transistors(3-7), have been proposed as replacements for the planar devices used today, and also for applications in biosensing(8-10) and power generation(11). The successful operation of such devices will depend on our ability to precisely control the location and number of active impurity atoms in the host semiconductor during the fabrication process. Here, we demonstrate that the free carrier density in semiconductor nanowires is dependent on the size of the nanowires. By measuring the electrical conduction of doped silicon nanowires as a function of nanowire radius, temperature and dielectric surrounding, we show that the donor ionization energy increases with decreasing nanowire radius, and that it profoundly modifies the attainable free carrier density at values of the radius much larger than those at which quantum(12,13) and dopant surface segregation(14) effects set in. At a nanowire radius of 15 nm the carrier density is already 50% lower than in bulk silicon due to the dielectric mismatch(15) between the conducting channel and its surroundings.