Electron mobility anisotropy in (Al,Ga)Sb/InAs two-dimensional electron gases epitaxied on GaAs (001) substrates

The electron mobility anisotropy in (Al,Ga)Sb/InAs two-dimensional electron gases with different surface morphology has been investigated.Large electron mobility anisotropy is found for the sample with anisotropic morphology,which is mainly induced by the threading dislocations in the InAs layer.For the samples with isotropic morphology,the electron mobility is also anisotropic and could be attributed to the piezoelectric scattering.At low temperature (below transition temperature),the piezoelectric scattering is enhanced with the increase of temperature,leading to the increase of electron mobility anisotropy.At high temperature (above transition temperature),the phonon scattering becomes dominant.Because the phonon scattering is isotropic,the electron mobility anisotropy in all the samples would be reduced.Our results provide useful information for the comprehensive understanding of electron mobility anisotropy in the (Al,Ga)Sb/InAs system.

Energy-band engineering by 2D MXene doping for high-performance homojunction transistors and logic circuits

The homojunction based on Ti_(3)C_(2)T_(x) MXene-doped In_(2)O_(3) and indium oxide as the channel layer is real-ized in high-performance metal oxide thin film transistors(TFTs).Doping of MXene into In_(2)O_(3) results in n-type semiconductor behavior,realizing tunable work function of In_(2)O_(3) from 5.11 to 4.79 eV as MXene content increases from 0 to 2 wt.%.MXene-doped In_(2)O_(3)-based homojunction TFT presents optimal per-formance with electron mobilities of greater than 27.10 cm^(2)/(V s)at 240°C,far exceeding the maximum mobility of 3.91 cm^(2)/(V s)for single-layer In_(2)O_(3)TFTs.The improved performance originates from boosting of a two-dimensional electron gas(2DEG)formed at carefully engineered In_(2)O_(3)/MXene-doped In_(2)O_(3)ox-ide homojunction interface.Besides,the transformation in conduction mechanism leads to better stability of MXene-doped In_(2)O_(3) homojunction devices compared to undoped bilayer In_(2)O_(3).Low-frequency noise further illustrates that doping MXene into In_(2)O_(3) helps to reduce the device trap density,demonstrating excellent electrical performance.A resistor-loaded unipolar inverter based on In_(2)O_(3)/0.5%MXene-In_(2)O_(3)TFT has demonstrated full swing characteristics and a high gain of 13.The effective doping of MXene into constructed homojunction TFTs not only contributes to improved stability,but also provides an ef-fective strategy for designing novel homojunction TFTs for low-cost oxide-based electronics.

Origin of the giant persistent photoconductivity in LaAlO_(3)/SrTiO_(3)heterostructures probed by noise spectroscopy

LaAlO_(3)/SrTiO_(3)(LAO/STO)heterostructures have shown a strong persistent photoconductivity(PPC)at room temperature.The abnormally strong PPC has attracted immense research interest due to its possible applications in optically-tunable electronic devices.Despite its promise,the fundamental understanding of the PPC in the LAO/STO heterostructures is still elusive.Herein,we report that the giant PPC origi-nates from the photo-induced valence change in oxygen vacancies near the LAO/STO interface.Our spec-tral analysis of the photocurrent and the model-fitting study consistently show that the ionized oxygen vacancies near the interface are neutralized during the electron relaxation process.They hinder the complete relaxation of the photoexcited electrons by the deeply-located oxygen vacancies and result in the strong PPC.The change in the ionization state distribution of the oxygen vacancies is probed by the per-sistent noise behavior at the frequency between 1 kHz and 20 kHz regime.These results provide insight into the role of oxygen vacancies in influencing the internal charge distribution and triggering the PPC phenomena in complex oxide heterostructures.