Banknotes boost ultraviolet LED firm's cash flow

04 Sep 2007

A Japanese company is replacing conventional UV bulbs with GaN LEDs to study banknotes.

UV LED manufacturer Nitride Semiconductors Co is making the most of the advantages its products offer over conventional UV bulbs, ejecting the latter from lucrative applications such as counterfeit banknote detection.

LED sales have been growing steadily since Nitride entered full-scale production at its site in Naruto City, Japan, in 2003, and have now grown to the point where the company is capable of making 10 million LEDs per month.

The company reportedly developed its technology with a maker of money-handling machines who sought to benefit from the improved efficiency and smaller size offered by LEDs.

Such counterfeit detection applications range from rapid integrated counter/validator machines aimed at banks and casinos, to cheap and simple keyring and pen lights.

LED production at Nitride is performed using a novel MOCVD approach developed in association with Shiro Sakai of Tokushima University, who subsequently became a director of the company.

Rather than the InGaN emitting layer used in blue LEDs, Nitride's MOCVD technique grows an AlInGaN emitting layer to achieve wavelengths below 380 nm.

Nitride claims to be the only supplier of bare UV LED die, for packaging by other companies, and also currently supplies LEDs already packaged as lamps and modules, as well as selling GaN epiwafers.

One firm that might counter that claim is the US company Sensor Electronic Technology, which has been supplying Seoul Optodevice with UV LED epiwafers since the two signed up to a strategic partnership just over a year ago (see related story). However, that supply deal did see each of the two companies take an equity position in the other.

Nitride Semiconductors is now looking to produce UV LEDs for use in developing photocatalysts, for example in curing resins and coatings, applications which demand a significant hike in power output.

This power increase is also the key to the optimistic outlook held by Nitride's CEO Yoshihiko Muramoto.

According to his statement on the company's website, he hopes for a future where UV LEDs combine with red, green and blue phosphors to provide true warm white lighting, find their way into TVs and general lighting, and ultimately replace all existing light emitting products.

• Nitride Semiconductor has recently released a range of surface mount device UV LED lamps, with wavelengths ranging from 365–375 nm and typical optical output power of 3.5 mW at 20 mA.

It has also released a high-power module, containing 27 LED chips, which emits light at 375 nm with a typical optical output power of 120 mW at 180 mA.

See Nitride's website for more details.