A nagging problem in today’s GaN based LED production is the inability to measure and control the real wafer temperature during epitaxial growth. LayTec has developed a new solution that provides precise measurement of GaN real surface temperature: Pyro 400 monitoring system.

Unlike conventional infrared pyrometry, which can only detect the susceptor surface temperature under sapphire or SiC wafers, Pyro 400 is the first real solution for measuring the exact surface temperature of  GaN layers using pyrometry at 400 nm. At this wavelength GaN absorbs and thermally emits light.

Pyro 400 provides excellent insight into the correlation between the wafer bow and the real wafer surface temperature. It is well known that wafer surface temperature measurements during III-Nitride epitaxy are inhibited by the transparency of the substrate material at the usual wavelength of pyrometry (950 nm). Up to now it was hardly possible to verify the influence of wafer bowing on temperature uniformity directly. Since the correlation between the bowing and the temperature is critical for III-Nitride process yield enhancement, we use Pyro 400 to measure the real GaN surface temperature directly.

For more technical information and measurement results please download the Application Note >