New oxide and semiconductor combination builds new device potential

  • Insulating oxides are oxygen containing compounds that do not conduct electricity, but can sometimes form conductive interfaces when they’re layered together precisely.
  • The conducting electrons at the interface form a two-dimensional electron gas (2DEG) which boasts exotic quantum properties that make the system potentially useful in electronics and photonics applications.
  • Researchers have grown a 2DEG system on gallium arsenide,a semiconductor that’s efficient in absorbing and emitting light.
  • This development is promising for new electronic devices that interact with light, such as new kinds of transistors, superconducting switches and gas sensors. This will act as a building block for oxide electronics.
  • Oxide 2DEG was used for generating electrons that behave like gas or liquid while sandwiching oxides together.
  • They have much higher electron densities, which pave way for electronics application. This have interesting quantum properties i.e) combination of magnetic behaviour and superconductivity.
  • Only small pieces of oxide crystals are obtainable. If oxides are grown on large scale they will be used in real world application.
  • Growing oxide 2DEGs on semiconductors also allows researchers to better integrate the structures with conventional electronics.
  • Enabling the oxide electrons to interact with the electrons in the semiconductor could lead to new functionality and more types of devices.
  • Most semiconductors react with oxygen in the air and form a disordered surface layer, which must be removed before growing these oxides on the semiconductor.
  • For silicon, removal is relatively easy ,,researchers heat the semiconductor in vacuum.
  • This approach, however, doesn’t work well with gallium arsenide. Instead they coated arsenic, which protects the semiconductor surface from air while they transfer the wafer into an instrument that grows oxides using a method called Molecular beam epitaxy.
  • This allows one material to grow on another while maintaining an ordered crystal structure across the interface.
  • The researchers gently heated the wafer to evaporate the thin arsenic layer, exposing the pristine semiconductor surface beneath.
  • They then grew an oxide called SrTiO3 on the gallium arsenide and, immediately after, another oxide layer of GdTiO3. This process formed a 2DEG between the oxides.
  • The ability to couple or to integrate these interesting oxide two-dimensional electron gases with gallium arsenide opens the way to devices that could benefit from the electrical and optical properties of the semiconductor

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