Structures, Oxidation, and Charge Transport of Phosphorus‐Doped Germanium Nanocrystals

Abstract

The doping of semiconductor nanocrystals (NCs) is crucial for the optimization of the performance of devices based on them. In contrast to recent progress on the doping of compound semiconductor NCs and silicon NCs, the doping of germanium (Ge) NCs has lagged behind. Here it is shown that Ge NCs can be doped with phosphorus (P) during synthesis by a nonthermal plasma. It is found that there are more P atoms in the NC near‐surface region than in the NC core. P doping modifies the surface state of Ge NCs. Compressive strain can be incuced in Ge NCs by P which can explain the P‐doping‐enhanced oxidation resistance of Ge NCs. Stable dispersions of P‐doped Ge NCs in acetonitrile can be cast to produce films for field‐effect transistors (FETs). FET analysis shows that the electrical conductivity and electron mobility of a Ge‐NC film increase with the increase of the P doping level, although the electrical activation efficiency of P in the Ge‐NC film is low. Finally, atomic layer deposition of aluminum oxide at the surface of P‐doped Ge NCs is shown to improve the performance of the FETs.

Microscopic Understanding of the Carrier Transport Process in Ge Nanocrystals Films

“…It was interesting to find that Hall mobilities were significantly increased from 0.14 cm 2 /V⋅s for the as-deposited film to 182 cm 2 /V⋅s for the Ge NCs film annealed at 500 ∘ C, which are improved more than three orders of magnitude after annealing. Compared with any other work investigating the electronic properties of Ge NCs, our values of Hall mobility are more outstanding than those of previous reports [24,25]. It is well known that the enhanced Hall mobility after annealing is actually attributed to the formation of Ge NCs in the films [12].…”

Формирование светоизлучающих в ИК-диапазоне нанокристаллов германия в плeнках Ge:SiO-=SUB=-2-=/SUB=-

“…В то время как HК Si изучены достаточно полно, гораздо меньше работ было посвящено исследованию НК Ge [16][17][18][19][20][21][22][23][24][25], либо НК Ge x Si 1−x , встроенных в диэлектрические матрицы [26][27][28][29][30][31][32], или исследованию нанопорошков Ge x Si 1−x [33,34]. Стоит отметить, что НК Ge имеют ряд преимуществ.…”

Density functional theory study on the boron and phosphorus doping of germanium quantum dots

“…[36][37][38][39][40] It is only recently that Ge QDs have been doped with boron (B) and phosphorus (P) by using a gas-phase synthesis approach. 41,42 It is found that both B and P atoms prefer occupying the near-surface region of Ge QDs, rather than the core of the QDs. The conductivity of Ge-QD lms may be effectively modulated by the doping of Ge QDs with B and P. 41,42 It is well known that theoretical simulation is critical to understanding on the doping mechanism of semiconductor QDs.…”

“…41,42 It is found that both B and P atoms prefer occupying the near-surface region of Ge QDs, rather than the core of the QDs. The conductivity of Ge-QD lms may be effectively modulated by the doping of Ge QDs with B and P. 41,42 It is well known that theoretical simulation is critical to understanding on the doping mechanism of semiconductor QDs. As a powerful theory for the investigation on the structural and electronic properties of materials, density functional theory (DFT) has been extensively employed to study the doping of a variety of semiconductor QDs such as the group IV counterpart of Ge QDs-silicon (Si) QDs.…”