Compound III-Nitride semiconductor materials have seen, in the last decade, extensive applications, mainly in light emitting diodes (LEDs) and high-power/high frequency high electron mobility transistors (HEMTs). In these areas, devices have reached commercialization stage. In this presentation, recent results concerning novel fields of III-Nitride hetero/nanostructures applications will be presented, concerning:
- (i) GaN quantum dots embedded in dielectrics for non-volatile memory application.
- Nanocrystal non-volatile memories (NC-NVM) approaches have attracted significant interest for CMOS and flexible electronics applications. They offer advantages in terms of devices’ operation speed and charge retention time. Utilization of III-Nitride quantum dots, with negative conduction band offsets (NCBO), with respect to Si, can lead to improved NVM devices. We will report on successful realization of such NVM devices, through a fully CMOS compatible methodology, demonstrating significant memory windows remaining after ten years extrapolation.
- (ii) Förster resonant energy transfer (FRET) between III-N quantum wells and light emitting polymers (LEPs) for advanced LED applications.
- FRET is a non-radiative, particularly efficient energy transfer mechanism, which can be employed to significantly enhance performance of LEDs for lighting applications. However, achievement of FRET efficient hybrid nitride-polyfluorene structures is particular challenging, since the realization of high quantum yield, near surface SQWs with emission characteristics well matched to the polymers’ optical properties is required. Investigations of thin PFO film properties and of the influence of structural parameters on the efficiency of energy transfer mechanism has been performed and hybrid structures with FRET efficiencies up to 70% have been demonstrated.
- (iii) III-Nitride resonant tunneling diodes (RTDs).
- Despite intensive efforts by many research groups, truly functional nitride RTD devices are yet to be demonstrated. Complex dynamic phenomena involving negative differential resistance, charge trapping and multistability in AlGaN/GaN double barrier RTDs will be presented. Towards the goal of achieving functional RTDs, the role of strong piezoelectric fields, present in the III-N heterostructures, is investigated and ways to overcome their deleterious effects are proposed.