The suitability of atomic-layer-deposited (ALD) Ti(Al)N GaAs surface
passivation and protection has been investigated. Ti(Al)N-film were
fabricated by using titanium tetrachloride (TiCl₄), trimethyl
aluminum (TMA) as a reducing agent and ammonia (NH₃) at 275 ^oC. The
passivation effect was studied by using GaAs/InGaAs near surface
quantum well (NSQW) structures, where photoluminescence (PL)
intensity measurement was used as an indicator for the effectivity
of passivation. Passivation reduces surface states which can be
recombination center for the carriers. Radiative recombination
decreases due to tunneling of carriers from quantum well to surface
when surface states in energy bandgap is increased. The number of
surface states can be reduced by depositing appropriate material on
the surface. In this work Ti(Al)N was deposited on NSQW resulting
eight times higher PL intensity compared to PL intensity of
uncovered reference sample. Ti(Al)N passivated NSQW protected by
aluminum oxide (Al₂O₃) and titanium oxide (TiO₂) layers was also
studied. PL intensity diminished when oxide layers
were used but protective effect was still observable when compared
to NSQW samples witch were covered only with Al₂O₃ or TiO₂. The temperature
stability of Ti(Al)N-covered NSQW was tested. It came out that
Ti(Al)N-covered NSQW doesn't luminesce after 400 ^oC annealing.
Thermal properties of the film were studied by using X-ray
reflectivity. Titanium nitride layers manufactured on Si (100) substrates. XRR-measurement was made before and after 400 ^oC annealing and preliminary test showed that the
thermal treatment didn't influenced to the film significantly. This study shows that
low temperature ALD Ti(Al)N is promising material for GaAs surface
passivation and protection when post deposition temperature is
limited well below 400 ^oC.

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