Switching behaviour and high frequency response of amorphous carbon double-barrier structures

In order to produce fast memory switching devices fabrication of double-barrier resonant tunnel diodes (DB-RTD) based on amorphous semiconductors with a prominent signature of resonant tunnelling and negative differential resistance (NDR) was attempted. We have developed DB-RTDs of amorphous carbon and showed unique features including NDR peaks, quantized conductance and switching effects in these structures. From the analysis of these experimental data the effective mass of electron of about 0.07 times the free electron mass, a high value of mobility and long coherence length of electrons in this low dimensional disordered system is derived. At higher operational bias voltage we recorded periodic current steps, which are explained by the creation of 1D channels in this structure. These features suggest ballistic conduction. We are able to tune the switching characteristics of these structures in the presence of microwave frequency at about 100 GHz which resembles a quantum well capacitor with a fast relaxation time. The increase of conductance at a particular bias, in the presence of microwave frequency can be explained through an increase of mobility and increased relaxation time of electrons. A carbon-based memory suitable for very fast operation, compared to other organic polymer systems is suggested.