MBE growth of nitride-arsenides for long wavelength opto-electronics

Until recently, the operating wavelength of opto-electronic devices on GaAs has been limited to below 1 μm due to the lack of III-V materials with close lattice match to GaAs that have a bandgap below 1.24 eV. To enable devices operating at 1.3 μm on GaAs, MBE growth of a new III-V material formed by adding small amounts of nitrogen to InGaAs was developed.; The growth of group III-nitride-arsenides (GaInNAs) is complicated by the divergent properties of the alloy constituents and the difficulty of generating a reactive nitrogen species. Nitride-arsenide materials are grown by molecular beam epitaxy (MBE) using a radio frequency (rf) nitrogen plasma source. The plasma conditions that maximize the amount of atomic nitrogen versus molecular nitrogen are determined using the emission spectrum of the plasma. To avoid phase segregation, nitride-arsenides must be grown at relatively low temperatures and high arsenic overpressures. It is shown that the group III growth rate controls the nitrogen concentration in the film.; Absorption measurements allow the establishment of a range of GaInNAs alloys yielding 1.3 μm emission. The optical properties of GaInNAs and GaNAs quantum wells (QWs) are investigated with photoluminescence (PL) measurements. The peak PL intensity increases and peak wavelength shifts to shorter wavelengths when annealing. The increase in luminescence efficiency results from a decrease in non-radiative recombination centers. As the impurity concentration in the GaInNAs films is low, crystal defects associated with nitrogen incorporation were investigated and improvements in crystal quality after anneal were observed. Nuclear reaction channeling measurements show that as-grown nitride-arsenides contain a considerable amount of interstitial nitrogen and that a substantial fraction of the non-substitutional nitrogen disappears during anneal. Secondary ion mass spectroscopy depth profiling on GaInNAs quantum wells shows that during anneal, the nitrogen diffusion is more pronounced than indium diffusion, hence nitrogen diffusion is also the major cause of the shift during the anneal process of GaInNAs QWs.; To limit nitrogen diffusion, the GaInNAs QWs were inserted between GaAsN barriers. This also resulted in longer wavelength emission due to decreased carrier confinement energy. This new active region resulted in devices emitting at 1.3 μm.