| AVS 64th International Symposium & Exhibition | |
| Electronic Materials and Photonics Division | Thursday Sessions |
| Session EM+NS-ThA |
| Session: | Wide and Ultra-wide Band Gap Materials for Electronic Devices: Growth, Modeling, and Properties |
| Presenter: | Daniel Seidlitz, Georgia State University |
| Authors: | D. Seidlitz, Georgia State University B.G. Cross, Georgia State University Y. Abate, Georgia State University A. Hoffmann, Technical University of Berlin, Germany N. Dietz, Georgia State University |
| Correspondent: | Click to Email |
In this study, we will present results of the in-situ plasma emission spectroscopy (PES) of the plasma activated nitrogen species during the growth of GaN/InN heterostructures by MEPA-MOCVD in correlation to their optical and structural characteristics.
Indium-rich InGaN semiconductors are of high interest due to the high electron mobility which enables ultrafast electronics operating in the THz regime. In conventional MOCVD, indium incorporation above 25 % is a challenge due to the vastly different partial pressures between InN and GaN and the lattice mismatch between the binaries. Migration enhanced plasma-assisted MOCVD is a kinetic stabilized growth surface approach to reduce the partial pressure difference between the InN and GaN. It also replaces the traditional ammonia precursor source for nitrogen through energetically controlled ionized nitrogen species (N*/NH*/NHx*), generated by a radio-frequency hollow cathode (13.56 MHz) with an output power between 50-600 W. The plasma-excited species are tailored in the gas phase and directed to the growth surface in the afterglow regime of the remote plasma utilizing the kinetic energies of the active nitrogen species to achieve a stable growth surface. Altering the process parameters like reactor pressure and nitrogen flux allows variation of the kinetic energies. A grid between the plasma source and the growth surface enables the control of the charged species reaching the growth surface and with it the electrostatic interactions in the InN/GaN growth process and the resulting layer properties. In-situ real-time plasma emission spectroscopy (PES) is used to monitor and identify the active nitrogen species close to the hollow cathode as well as near the growth surface. Comparison of the spectra could help to determine which nitrogen species promote the growth of group III- nitride materials.
Optoelectronic and structural qualities such as free carrier concentration as well as crystallinity, growth rate, the surface morphology of the GaN and InGaN films are examined using ex-situ characterization techniques (Raman, AFM, FTIR). We will present a correlation of the in-situ and ex-situ results as a function of the explored growth parameters like growth temperature, plasma power, and reactor pressure.