Negative differential resistance of CaF 2 /Si double barrier resonant tunneling diodes fabricated using plasma etching mesa isolation process

We demonstrated the negative differential resistance (NDR) characteristics in CaF2/Si double barrier resonant tunneling diodes (DBRTDs) which have mesa structure isolated by the plasma etching process using CF4/O2 plasma. Clear NDR characteristics with a peak to valley current ratio of 79 and a current density of 1–10 kA cm−2 was obtained from a CaF2/Si DBRTD mesa-isolated using CF4/O2 plasma etching at room temperature. Furthermore, any degradation of performance of the DBRTD caused by dry etching has not been observed. The NDR characteristics were reasonably reproduced by theoretical analysis based on a ballistic transport model. These results implied that the plasma etching process using CF4/O2 enables CaF2/Si heterostructure devices to be implemented into the Si-based integrated circuit technology.