High sensitive thermal sensors in heat spreading diamond films for industrial applications

Diamond has been widely used as an electrical insulating heat spreading material in electronic thermal management applications since relatively cheap polycrystalline CVD diamond films have been available. In this work, the authors present the use of diamond heat spreaders in a single addressable diode laser array device which is useful for end-pumping solid state light. For this application, precise measurement and control of the junction temperatures of the diode lasers are required in order to control the wavelength of the emitted light. For this purpose, they inserted one thermistor per gap between all laser zones by doping the diamond substrates with boron. For the optimization of different doping profiles and metallization schemes were investigated with Auger and electrical measurements. They found out that the standard trilayer scheme (Ti/Pt/Au) can only be used below 700°C in contrast to the results which could be found in the literature. With their optimized thermistors, they are able to measure a shift of the wavelength of the emitted laser light due to a change of their temperature of less than 0.1 nm