Extraordinary field emission of diamond film developed by microwave plasma jet chemical vapor deposition*

The present work reports both numerical and experimental studies of reconditioning a microwave plasma jet chemical vapor deposition (MPJCVD) system for diamond film growth. A three-dimensional plasma fluid model is constructed for understanding and conditioning the MPJCVD system and optimizing its operating conditions. The methodology solves electromagnetic waves and plasma dynamics selfconsistently using an adaptive finite element method. The whole system has been modeled under varying parameters including the reactor geometry, microwave power, and working gas pressure. Using an operating condition identical to the optimized simulation results, the thin diamond film has been fabricated successfully. The SEM image reveals the presence of a diamond film uniformly distributed with particles at a size of ~1 mm. The field emission from the diamond film grown from this MPJCVD shows extraordinary properties, i.e., extremely low turn-on voltage and high current density. The turn-on electric field could be as low as ~4 V/mm. This work provides more physical insights of the system and improves the performance of design. It may find applications in surface hardening and bright field electron emission.