Nano-channel electroporation (NEP) is a new technology for cell transfection, which provides superior gene delivery and cell viability to conventional bulk electroporation (BEP). In NEP, cells laid on a porous...

The etching of epitaxially grown perovskite oxide BaSnO3 (BSO) and BaTiO3 (BTO) thin films is studied using Cl-based (BCl3/Ar) and F-based (CF4/Ar) plasma chemistries in an inductively coupled plasma reactive ion etching (ICP-RIE) system for the development of field effect transistors (FETs). It is found that the BCl3/Ar process has a time-independent and a higher etch rate and creates a smooth etched surface, while the etch rate of BSO and BTO in CF4/Ar plasma decreases with the etching time duration. For the BCl3/Ar etching process, the etch rate increases with both ion density and ion energy, suggesting the combination of chemical plasma etching and physical ion sputtering mechanisms. Using the Cl-based etching process, BaSnO3 and BaTiO3 heterojunction FETs are developed. The devices with a gate length of 1.5 μm have a saturation current density of 287.6 mA/mm, a maximum transconductance of gm = 91.3 mS/mm, an FET mobility of 45.3 cm2/V s, and a threshold voltage of −1.75 V. The etching processes developed in this work will enable further development of perovskite oxide heterostructure electronic devices.

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We report an electron transport study of an La-doped perovskite oxide BaSnO3 thin film grown by molecular beam epitaxy on (110) DyScO3 as a function of electron concentration, by etching the film step-by-step with nanometer precision. Inductively coupled plasma-reactive ion etching with BCl3/Ar plasma is used for etching depth control. The local doping and electron density are experimentally determined after each etching step. The results show that the electron mobility is dominated by threading dislocations if the electron concentration is below 7.8 × 1019 cm−3, while ionized impurities and phonon scattering become more dominant at electron concentrations greater than 1.2 × 1020 cm−3. The charging state of thread dislocations is estimated to be 6.2. Furthermore, using the etch process to control the electron concentration and channel thickness, a gate-recessed ferroelectric field effect transistor is fabricated with 10 nm HfO2 as a gate dielectric. The device exhibits a saturation current of 29.9 mA/mm with a current on/off ratio of Ion/Ioff = 8.3 × 108 and a ferroelectric polarization charge density of 1.9 × 1013 cm−2. Under the forward gate bias sweep, the device operates in the enhancement mode with a threshold voltage of 3 V. Under the reverse gate sweeping bias, the device operates in the depletion mode with a threshold voltage of –1.5 V.

BaSnO3, a high mobility perovskite oxide, is an attractive material for oxide-based electronic devices. However, in addition to low-field mobility, high-field transport properties such as the saturation velocity of carriers play a major role in determining device performance. We report on the experimental measurement of electron saturation velocity in La-doped BaSnO3 thin films for a range of doping densities. Predicted saturation velocities based on an LO-phonon emission model show good agreement with measurements indicating that optical phonon emission is the likely mechanism for velocity saturation in La-doped BaSnO3 films. Density-dependent saturation velocity in the range of 1.6x10 7 cm/s reducing to 2x10 6 cm/s is predicted for δ-doped BaSnO3 channels with carrier densities ranging from 10 13 cm -2 to 2x10 14 cm -2 respectively. These results are expected to aid the informed design of BaSnO3 as the active material for high-charge density electronic transistors.