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Articles you may be interested inStrain reduction and crystal improvement of an InGaN/GaN quantum-well light-emitting diode on patterned Si (110) substrate Appl.Effects of In composition on ultraviolet emission efficiency in quaternary InAlGaN light-emitting diodes on freestanding GaN substrates and sapphire substrates

We report on the improvement of light output power of InGaN/GaN blue light-emitting diodes (LEDs) by lateral epitaxial overgrowth (LEO) of GaN using a pyramidal-shaped SiO(2) mask. The light output power was increased by 80% at 20 mA of injection current compared with that of conventional LEDs without LEO structures. This improvement is attributed to an increased internal quantum efficiency by a significant reduction in threading dislocation and by an enhancement of light extraction efficiency by pyramidal-shaped SiO(2) LEO mask.

Lanthanum-modified lead titanate (PLT) thin films were fabricated on Pt/Ti/SiO2/Si substrate using the sol-gel method and rapid thermal annealing technique. The pyroelectric coefficient, and the infrared responsivity and the detectivity of the films were measured using static and dynamic methods, respectively. The ferroelectric properties were also measured. The pyroelectric coefficient increased from 1.3 to 2.5 nC/cm2· K with increasing La content. However, these low coefficients of PLT films are due to their crystal quality and orientations. The infrared response properties of PLT films depended on their thermal time constants. τ t (thermal time constant) for the PLT films decreased with the La contents increasing. The effects of back surface etching on the responsivity and the detectivity were also discussed.

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