Advanced GalnG/GaN Multiple Quantum Wells Revealed Through THz Emission Spectroscopy

A collaboration between a team of Osaka University, Bielefeld University, and Technical University of Braunschweig in Germany came close to finding the complicated optical response in the wide bandgap semiconductor multiple quantum wells and how the atomic-scale lattice vibrations helps in generating free space terahertz emissions. The following research is projected to pave new way for the transition from laser-based terahertz emission microscopes to nano-seismology for wide-bandgap quantum devices. Terahertz waves are generated by ultrafast operation that occur in a material. They are often observed by researchers in order to pinpoint various processes at a quantum level.

This process included observing simple bulk semiconductor to identifying advanced quantum materials such as multiple quantum wells. The researchers measured multifunctional response within GalnN/GaN multiple quantum wells (MQWs). This included the dynamic screening effect of the build-in fields, capacitive charge between GaN & GalnN quantum wells, and the acoustic wave beams that are launched by the stress release between the consecutive compounds. All these functions were observed by the researchers by discharging Thz emissions into free space. It was concluded that the pulsating acoustic waves possess a new technique that can be used to determine the thickness of buried structures at the resolution of 10nm on the wafer scale.

The probing and identifying of structures in semi-acoustic devices at an extremely high resolution is a rather unexplored subject. The current trend of application includes acoustically driven electromagnetic THz emissions into free space for GalnN/GaN MWQs placed between GaN material. The researchers further tested their hypothesis by organizing a THz emission spectroscopy, opto-THz science, and wide-bandgap/quantum wells semiconductor material science by taking 3D dynamic characterization between buried active layers. The researchers further conclude that a 3D tool is required in enhancing the ultrafast carrier dynamics, strain, physics, phonon dynamics, and ultrafast dielectric responses in a local non-contract and non-destructive manner.