Current–voltage characteristics in double-barrier resonant tunneling diodes with embedded GaAs quantum rings

We report current–voltage (I–V) characteristics in GaAs/AlGaAs double-barrier resonant tunneling diodes (DB-RTDs), in which GaAs quantum rings (QRs) that are grown on a 4-nm thick GaAs are sandwiched between AlGaAs barrier layers. The QRs prepared by droplet epitaxy are 40 nm wide and 4 nm high. Negative differential resistance (NDR) and asymmetric resonance feature are observed in the QR-embedded RTDs. From comparison with references, we conclude that the NDR feature is originated from the 4-nm thick QW, not QRs.