Structures, Electronic Properties and Carrier Transport Mechanisms of Si Nano-Crystalline Embedded in the Amorphous SiC Films with Various Si/C Ratios.

Dan Shan,Daoyuan Sun,Mingjun Tang,Ruihong Yang,Tao Tao,Yunqing Cao,Guangzhen Kang

doi:10.3390/nano11102678

Dan Shan, Daoyuan Sun + Show 5 more

Open Access

https://doi.org/10.3390/nano11102678

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Abstract

Recent investigations of fundamental electronic properties (especially the carrier transport mechanisms) of Si nanocrystal embedded in the amorphous SiC films are highly desired in order to further develop their applications in nano-electronic and optoelectronic devices. Here, Boron-doped Si nanocrystals embedded in the amorphous SiC films were prepared by thermal annealing of Boron-doped amorphous Si-rich SiC films with various Si/C ratios. Carrier transport properties in combination with microstructural characteristics were investigated via temperature dependence Hall effect measurements. It should be pointed out that Hall mobilities, carrier concentrations as well as conductivities in films were increased with Si/C ratio, which could be reached to the maximum of 7.2 cm2/V∙s, 4.6 × 1019 cm−3 and 87.5 S∙cm−1, respectively. Notably, different kinds of carrier transport behaviors, such as Mott variable-range hopping, multiple phonon hopping, percolation hopping and thermally activation conduction that play an important role in the transport process, were identified within different temperature ranges (10 K~400 K) in the films of different Si/C ratio. The changes from Mott variable-range hopping process to thermally activation conduction process with temperature were observed and discussed in detail.

Highlights

In the current studies, more and more attention has been focused on the Si nanocrystals (Si NCs) embedded in amorphous SiC (Si NCs:a-SiC) films due to their applications in nano-electronic and optoelectronic devices, including Si-based light-emitting diode, nonvolatile memories, biosensors, and especially the Si-based solar cells [1,2,3,4,5]
The present data demonstrate that different kinds of conduction mechanisms as Mott variable-range hopping, multiple phonon hopping, percolation hopping and thermally activation conduction contribute to the carrier transport process in B-doped Si NCs:a-SiC films at different temperature
B-doped Si NCs:a-SiC films with various Si/C ratios were fabricated by plasma enhanced chemical vapor deposition (PECVD) method

Summary

Introduction

More and more attention has been focused on the Si nanocrystals (Si NCs) embedded in amorphous SiC (Si NCs:a-SiC) films due to their applications in nano-electronic and optoelectronic devices, including Si-based light-emitting diode, nonvolatile memories, biosensors, and especially the Si-based solar cells [1,2,3,4,5]. Phosphorus (P)-doped Si NCs:a-SiC films were fabricated and both room temperature conductivity and Hall mobility were investigated [19]. For sample with low doping ratio, Hall mobility was improved with temperature, which indicated that the grain boundaries (GBs) scattering and ionized impurities scattering played a critical role in the carrier transport process. Our results underlines that the mobilities and carrier concentrations of Si NCs:aSiC films are gradually increased with the Si/C ratio, leading to an improvement of conductivities at room temperature. The present data demonstrate that different kinds of conduction mechanisms as Mott variable-range hopping, multiple phonon hopping, percolation hopping and thermally activation conduction contribute to the carrier transport process in B-doped Si NCs:a-SiC films at different temperature. The possible conduction mechanisms in films with different Si/C ratio are briefly discussed respectively

Experiment

Nanostructure

Room Temperature Electronic Properties

Temperature-Dependent Conductivity

Conclusions