研究目的
To further improve the electron emission efficiency of planar-type electron sources based on a graphene-oxide-semiconductor (GOS) for neutralizer cathode on nanosatellites by suppressing the damage of the insulating layer through decreasing the temperature growth of graphene.
研究成果
The study successfully improved the electron emission efficiency of GOS devices to 23.6% by lowering the graphene growth temperature to 800°C and annealing the devices in a vacuum. This represents a significant improvement over previous efficiencies, demonstrating the potential of GOS devices as efficient neutralizers for nanosatellites. Future work will focus on increasing the emission current by enlarging the emission areas or creating arrays of emission sites.
研究不足
The maximum emission current is still limited to 2.3 μA at 14 V due to the small emission area of 50 × 50 μm2, which is insufficient for nanosatellite neutralizers requiring at least a few mA. Further scaling up of the emission area or creating massive arrays of small emission sites is necessary while maintaining high emission efficiency.
1：Experimental Design and Method Selection:
The study revised the fabrication procedure of the GOS device to improve emission efficiency by using chemical vapor deposition (CVD) at lower temperatures (800°C or 900°C) compared to the previous temperature of 1050°C, and annealing the devices to decrease the work function of the graphene layer.
2：Sample Selection and Data Sources:
GOS devices were fabricated with emission areas of 50 × 50 μm
3：List of Experimental Equipment and Materials:
The fabrication involved thermal oxidation for SiO2 layer growth, CVD for graphene synthesis, photolithography for graphene etching, and electron beam vacuum evaporation for Ni/Ti electrode deposition.
4：Experimental Procedures and Operational Workflow:
The devices were annealed using a heat lamp at 300°C at a pressure of 10–5 Pa. Electron emission characteristics were measured by applying gate bias (VG) between the n-Si and the contact electrode.
5：Data Analysis Methods:
The electron emission efficiency (η) was evaluated as the ratio of the electron emission current (IA) to the total current (IC).
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