Ij Buss

Three-dimensional numerical modeling of emission from InSb light-emitting diodes with patterned surfaces

Full 3D numerical modeling is undertaken on light-emitting diode structures with patterned surfaces represented by regular, pseudorandomly disordered, and uniformly distributed random arrays of square holes to investigate both grating and random scattering phenomena. Unlike typical roughened surface LEDs, no recycling mirror is present below the source, enabling straightforward implementation in existing device designs. The period or feature width of the arrays is varied and the output emission intensity calculated. A maximum enhancement factor of ~2 is seen for both a disordered pattern with an array period of 1.7 μm and pattern depth of 0.4 μm and a particular random pattern with a feature width of 0.85 μm and depth of 0.4 μm. The enhancement is believed to be due to mitigation of both total internal reflection and Fresnel reflection phenomena at the semiconductor-air interface.

Finite-Difference Time-Domain Modeling of Periodic and Disordered Surface Gratings in AlInSb Light Emitting Diodes With Metallic Back-Reflectors

Two-dimensional finite-difference time-domain modeling is undertaken to study the optical behaviour of midinfrared AlInSb light-emitting diode devices with close metallic back reflectors. The location of the source and mirror is investigated in detail and optimised for peak emission at ¿0 = 4 ¿m. A periodic surface grating is added and it is found that greater than 98% of the light at a specific wavelength may be extracted for specific grating parameters, an enhancement of ~ 20-fold. A novel type of grating termed disordered-periodic is then studied and is shown to have a much broader spectral response with more than 50% of the power extracted across a broad wavelength range.

Measurement of mid-infrared alinsb light-emitting diodes with surface patterning

3D FDTD modelling is employed to design a surface pattern for mid-IR LEDs. Measured enhancement factors over an un-patterned device of 8% and 14% are found at 300 K and 25 K respectively.

3D modelling of enhanced surface emission using surface roughening

3D FDTD is used to study the effect of surface roughening on the emission of a point source embedded in GaAs with a mirror behind the dipole. Enhancement factors of 10 : 1 are observed.

3D Modelling of Enhanced Surface Emission using Surface Roughening

A 3D FDTD modelling is used to study the effect of surface roughening on the vertical emission of a point source emitting at lambda0=0.94 mum embedded in GaAs with a mirror behind the dipole. Enhancement of emission is seen at lambda0=1.95 mum for a rough-surface device with a perfect metal mirror placed 150 nm below the source

FDTD Modelling of Mid Infrared Disk Lasers

This paper presents 2D FDTD modelling of a disk resonator that could be used as a disk laser. Results are shown for mode spacing and good agreement with a simple Whispering Gallery Mode model is observed. The influence of direct coupled waveguides on modal behaviour is studied and a large reduction in cavity Q is observed.