A truncated-inverted-pyramid (TIP) chip geometry provides substantial improvement in light extraction efficiency over conventional AlGaInP/GaP chips of the same active junction area (∼0.25 mm2). The TIP geometry decreases the mean photon path-length within the crystal, and thus reduces the effects of internal loss mechanisms. By combining this improved device geometry with high-efficiency multiwell active layers, record-level performance for visible-spectrum light-emitting diodes is achieved. Peak efficiencies exceeding 100 lm/W are demonstrated (100 mA dc, 300 K) for orange-emitting (λp∼610 nm) devices, with a peak luminous flux of 60 lumens (350 mA dc, 300 K). In the red wavelength regime (λp∼650 nm), peak external quantum efficiencies of 55% and 60.9% are measured under direct current and pulsed operation, respectively (100 mA, 300 K).

We have fabricated and studied a violet (λ=403 nm) vertical cavity surface emitting laser structure, composed of an InGaN multiple quantum well active medium and a pair of high reflectivity dielectric mirrors. Lasing under high repetition rate (76 MHz) pulsed optical pumping has been achieved at temperatures up to T=258 K at average pump power of approximately 30 mW.

A method is described for fabricating a vertical cavity light emitting structure for nitride semiconductors. The process involves the separation of a InGaN/GaN/AlGaN quantum well heterostructure from its sapphire substrate an its enclosure by a pair of high reflectivity, low loss dielectric mirrors to define the optical resonator. We have demonstrated a cavity Q factor exceeding 600 in initial experiments, suggesting that the approach can be useful for blue and near ultraviolet resonant cavity light emitting diodes and vertical cavity lasers.

A vertical injection, light emitting InGaN quantum well diode has been demonstrated by separating the nitride heterostructure from its sapphire substrate by ultraviolet laser photoablation within a process scheme that allows transferring the devices to a host substrate. The incorporation of a dielectric multilayer stack to the device is shown to be a first practical step towards a resonant cavity light emitting diode.

Double crystal x-ray diffraction data is presented from the most extensive compliant substrate experiment to date. Five consecutive InGaAs–GaAs growths were performed simultaneously on GaAs-based thin film compliant substrates and thick reference substrates. The In0.07Ga0.93As layers were grown to thicknesses below and above the conventional critical thickness. It was found that InGaAs films grown on the compliant substrates have a larger critical thickness and slower strain relief than InGaAs grown on conventional GaAs substrates.