Resonant-tunneling triangular-barrier optoelectronic switch by gas source molecular beam epitaxy

We report a novel optical bistable device, resonant-tunneling triangular-barrier optoelectronic switch (R-TOPS), which consists of a double-barrier resonant-tunneling diode (DB-RTD) and a triangular-barrier phototransistor (TBP), grown by gas source molecular beam epitaxy (GSMBE). First, we studied the potential of the GSMBE to grow a DB-RTD and a TBP. The DB-RTD with In_0.53Ga_0.47As(well)/AlAs(barrier) exhibited clear negative differential resistance (NDR). Interfaces between In_0.53Ga_0.47As and AlAs in the DB-RTD were of good quality without dislocations in spite of the strained AlAs layers. On the other hand, the TBP with n⁺-i-δp⁺-i-n⁺ structure composed of In_0.53Ga_0.47As/In_0.52Al_0.48As layers was fabricated on InP, which was the first demonstration of a TBP at 1 μm wavelength range operation to our knowledge. On these basis, we fabricated the R-TOPS devices. Sharp NDR with clear bistability was successfully observed, and its characteristics were dependent on optical input power. Bistability was observed in the relation between input-light power and output-current. By connecting the device to a laser diode, clear optical bistability and sharp optical NDR property with high contrast and at low input-light power were also demonstrated. We found that both the TBP and the DB-RTD worked well in the R-TOPS grown by GSMBE.