Band Structure And Transport Mechanism Of Hydrogenated Nanocrystalline Silicon/Crystalline Silicon Heterojunction Diode

This paper studies the electronic properties of hydrogenated nanocrystalline silicon (nc-Si:H)/crystalline silicon (c-Si) heterojunction (HJ) diode, concentrating on the band offsets and transport mechanisms. Nc-Si:H thin film based HJ diode has recently attracted considerable attention for its potential values in device applications and theoretical research works. By fully understanding the electronic transport and heterojunction interface properties, we are able to develop the correct band structure, as well as the transport mechanisms under different temperature regions, and also to provide theoretical basis to make the HJ diode with higher performance and wider application fields.First we give a brief introduction of the nc-Si:H material and the nc-Si:H/c-Si HJ diode related research works, including the growth, physical properties and applications, etc. Since the up-to-date electronic properties of the nc-Si:H/c-Si HJ diode are still limited, which, however, is the key to understand the physical principle and improve its performance, the majority of our work is assigned to the following aspects: experimental setup (both hardware configuration and software develop), HJ band structure, HJ interface properties, transport mechanisms under different temperatures, and the quantum transport behavior under the low temperature.For the experimental setup, this paper present in detail the hardware connection and software development of the Capacitance-Voltage-Temperature (C-V-T) spectra and Current-Voltage-Temperature (I-V-T) spectra measurement system, concentrating on the instruments used in the system, which include Agilent 4284A LCR Meter, 15065 External Bias Testing Fixture, Keithley 2400 Source Meter and 2182 Nano-Voltage Meter. Detailed introduction of the software interface and usage has also been provided. In addition, the validity of the measurement system has been confirmed by utilizing the commercial diodes.As for the theoretical analysis and calculation, we use both the classical analytical Anderson model and novel numerical C-V Matching method to analyze the band structure of the nc-Si:H/c-Si, and successfully obtain the band offset and interface charge density parameters. Furthermore, based on the general rectifying model, qualitative analysis and quantitative calculation have been done to investigate the temperature-dependent I-V data, leading to the conclusion——the non-tunneling and tunneling transport on the high and low temperature ends, and transitional region in the middle. In addition, the periodical negative conductivity phenomenon has been discussed for the highly ordered nc-Si:H/c-Si HJ diode.