Semiconductor CVD diamond for electronic devices
Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
One of the strategies for enabling active electronic devices based on diamond is ‘delta doping’ with an electronically active impurity dopant (donor or acceptor). This strategy is proposed as a mechanism to overcome the high thermal activation energy of the known electronically active dopants, boron (0.32 to 0.37 eV) and phosphorous (05 to 0.6 eV) to create electronically mobile carriers (holes in the valance band or electrons in the conduction band) without sacrificing the mobility penalty resulting from heavily doped material. This concept of delta doping of diamond with boron was investigated in Diamond electronic laboratory organized for carrying out of grant “Semiconductor CVD diamond for high-power and high-frequency electronic devices” in Institute of Applied Physics of the Russian Academy of Sciences and in collaboration with St. Petersburg Electrotechnical University (LETI). Initial Hall effect measurements of the carrier concentrations and mobility of the holes indicates successful ‘delta doping’. We have designed and constructed a unique microwave plasma driven chemical vapor deposition reactor built solely for the purpose of delta doping. Key features of this reactor are an ultra-rapid reactant gas switching system, high velocity laminar flow, independent control of substrate temperature. Also, extreme care is taken to substrate preparation, quality and roughness. We report here our strategy to achieve successful delta doping of diamond with boron and initial electrical characterization of our delta layers with results better than that achieved by previous researchers. Also designs of some electronic devices based on this material are discussed.