CVD diamond represents a very attractive material for the fabrication of devices based onthermionic emission, due to the possibility to achieve a very low or even negative electron affinity(NEA) by a hydrogen surface termination.We present here a preliminary study on thermionic conversion from diamond thin films grown ondifferent substrates, ranging from silicon to engineered ceramic materials. In particular, amongthem, HfC-based ceramics have been selected for its integration with diamond in concentrated solarsystems. CVD polycrystalline and nanocrystalline diamond films were deposited by MW-CVD(MicroWave-Chemical Vapour Deposition) by varying also their doping.Thermionic performance was evaluated in an ultra-high-vacuum (pressure <10-8 Torr)characterization setup able to accurately control the emitter and collector temperatures.Experimental activity has been carried out to integrate the HfC-diamond system in a more complexconversion module that was tested in a concentrating solar system to verify the conversionperformance under operating conditions. These results are finally reported.
Thermionic emission from CVD poly- and nano-crystalline diamond films grown on different substrates
Alessandro Bellucci;Paolo Calvani;Emilia Cappelli;Grazia Cicala;Marco Girolami;Diletta Sciti;Laura Silvestroni;Daniele M. Trucchi
2014
Abstract
CVD diamond represents a very attractive material for the fabrication of devices based onthermionic emission, due to the possibility to achieve a very low or even negative electron affinity(NEA) by a hydrogen surface termination.We present here a preliminary study on thermionic conversion from diamond thin films grown ondifferent substrates, ranging from silicon to engineered ceramic materials. In particular, amongthem, HfC-based ceramics have been selected for its integration with diamond in concentrated solarsystems. CVD polycrystalline and nanocrystalline diamond films were deposited by MW-CVD(MicroWave-Chemical Vapour Deposition) by varying also their doping.Thermionic performance was evaluated in an ultra-high-vacuum (pressure <10-8 Torr)characterization setup able to accurately control the emitter and collector temperatures.Experimental activity has been carried out to integrate the HfC-diamond system in a more complexconversion module that was tested in a concentrating solar system to verify the conversionperformance under operating conditions. These results are finally reported.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
