Chlorine processes are widely used for the formation of waveguide structures in InP-based optoelectronics. Traditionally, ICP etching of InP in a Cl2-based plasma requires substrate temperatures in the range of 150–200 °C. This condition is mandatory, since during the etching process low-volatility InClx components are formed and at insufficient temperatures are deposited onto substrate, leading to the formation of defects and further impossibility of the formation of waveguide structures. The need to preheat the substrate limits the application of chlorine processes. This paper presents a method of ICP etching an InP/InGaAsP heterostructure in a Cl2/Ar/N2 gas mixture. A feature of the developed method is the cyclic etching of the heterostructure without preliminary heating. The etching process starts at room temperature. In the optimal etching mode, the angle of inclination of the sidewalls of the waveguides reached 88.8° at an etching depth of more than 4.5 μm. At the same time, the surface roughness did not exceed 30 nm. The selectivity of the etching process with respect to the SiNx mask was equal to 9. Using the developed etching method, test integrated waveguide elements were fabricated. The fabricated active integrated waveguide (p-InP epitaxial layers were not removed) with a width of 2 μm demonstrated an optical loss around 11 ± 1.5 dB/cm at 1550 nm. The insertion loss of the developed Y- and MMI-splitters did not exceed 0.8 dB.

A suspended quantum point contact and the effects of the suspension are investigated by performing identical electrical measurements on the same experimental sample before and after the suspension. In both cases, the sample demonstrates conductance quantization. However, the suspended quantum point contact shows certain features not observed before the suspension, namely, plateaus at the conductance values being non-integer multiples of the conductance quantum, including the “0.7-anomaly.” These features can be attributed to the strengthening of electron-electron interaction because of the electric field confinement within the suspended membrane. Thus, the suspended quantum point contact represents a one-dimensional system with strong electron-electron interaction.

Nonlinear vibrations of nanoelectromechanical beam fabricated from the GaAs/AlGaAs heterostructure containing two-dimensional electron gas are investigated. The measurement of time-averaged conductance is shown to be a sensitive method for the nanomechanical motion detection. The possibilities to excite high-amplitude (up to 20 nm) mechanical vibrations and to effectively detect them using the simple conductance measurement make such systems promising for practical applications. High-amplitude vibrations of the beam are shown to demonstrate softening nonlinearity. This can be attributed to the bending of the beam due to Euler buckling instability caused by the compressive stress though GaAs/AlGaAs heterostructures are typically considered as stress-free.