Development of a Deposition System for Research/Education in Materials Preparation for Field Effects Doping

Stanford University, Stanford CA

Investigators

Abstract

This grant supports development of a pulsed laser deposition system, a key component in a new deposition facility that optimizes the various layers required for field-effect doping in a highly controlled manner and with well-characterized interfaces. The system is built upon existing laboratory capabilities. The development should permit versatile and reliable field-effect structures to be fabricated that can routinely withstand the enormous electric field stresses inherently present in such structures. An aim is to allow very good control over the interfaces at which the field-effect doping occurs must be achieved. The use of the field effect to dope the surface of a material is a well-established technique in the study and application of semiconductors. Until recently it was believed that field-effect doping could not be usefully applied to conducting (metallic) materials. Recent results using both direct, voltage-biased capacitive field-effect structures and ferroelectric field-effect structures have demonstrated that quite substantial charge densities can be induced. In some cases the consequences of this field-effect doping have been dramatic. For example, Schoen, Batlogg and coworkers have achieved a superconducting transition temperature of 117K by means of field-effect doping into CH3Br intercalated carbon C60. These results both provide an existence proof that the field effect in conducting materials can be made to work and demonstrate dramatically the possibilities. These results represent the opening of a new era in the study of two-dimensional electronic systems, one of the most fertile areas of condensed matter physics over the past few decades. Concomitantly, they represent a particularly effective venue for the training of graduate students.