The diamond LED was developed by comprehensive research, and can be used at 400 degrees centigrade"

The Industrial Technology Research Institute has developed a deep UV LED with diamond as the semiconductor. Details will be held in the 09 year of the Application Physics Institute of the spring of, "the fifty-sixth Joint Conference on Applied Physics" (March 30th ~ April 2nd, University of Tsukuba) published (Lecture number: 1p-TC-9 ~ ~).

Luminescence demonstration of diamond LED produced by comprehensive research and development. Visible light is not the original ultraviolet, but the use of angular defects and other visual light. The actual intensity (unit wavelength) is about 20 times of visible light.

The development of deep UV LED using 2mm Square diamond substrate stacked p-i-n structure diamond semiconductor design. The use of light-emitting wavelength of 235nm deep uv. The output power is 30 W when injected into the 320mA current. "Is now close to the practical level" (production of energy technology research department of the main research fellow, University of Tsukuba, mathematical physics and chemistry research grant Yamazaki So).

The structure of the diamond LED

According to the production of comprehensive research revealed that the LED has two characteristics: (1) even if the current efficiency is still large current increase, (2) high temperature resistance. For example, even through the diameter of 120 m electrode current density of more than 2000A/cm2 current, the luminous efficiency will not reach saturation, but continue to rise. At present, the maximum current density of the deep UV LED using competitive semiconductor AlGaN is about 500A/cm2.

The temperature dependence of the emission spectrum at the injection current of 50mA. At 421 DEG C, the luminous intensity is still rising.

At high temperature, even if the temperature is increased from room temperature to 420 DEG C, the intensity of the luminescence is not decreased, but the intensity is enhanced. The diamond LED is different from the ordinary LED, using the "exciton" as the principle of luminescence. Exciton is electron and hole pairs moving like particles. However, in general it is not heat resistant, and most of the excitons will soon break. The diamond LED generated exciton is very stable, even if the temperature is not broken at 600 degrees (production of energy technology research department of the Ministry of energy and energy foundation, special researcher Makino Junharu). This is the reason for high temperature.

Substantial cost reductions will soon be realized

Prior to this, the diamond used as the base of the diamond LED price is very high, and can only get a few mm square diamond floor, unable to achieve practical level. In this regard, Makino, said: "currently being developed in the silicon wafer stacked polycrystalline diamond film technology. Efficiency is only 1 lower than the development of LED. Due to the use of silicon and methane and other very common materials, so put into practice, can be very low cost of manufacturing diamond LED".