Single crystal CVD diamond has many desirable properties as a radiation detector; exceptional radiation hardness and physical hardness, chemical inertness, low Z (close to human tissue, good for dosimetry and transmission mode applications), wide bandgap (high temperature operation with low noise and solar blind), an intrinsic pathway to fast neutron detection through the 12 C(n,α) 9 Be reaction. This combination of radiation hardness, temperature tolerance and ability

Limitations associated with light emitting diodes (LEDs) operating under high current densities due to the efficiency droop has created a need to look for alternative light sources; here we report investigations on the potential of laser diodes (LDs) for high brightness lighting solutions. High power laser diodes require phosphor targets with certain performance criteria such as high thermal conductivity, efficiency and structural geometry. Here we examine the possibility of using single crystal YAG:Ce phosphor materials as potential targets for generation of light via laser diodes. We report on the emission properties of the crystals with different sizes and examine the effect of laser beam incident angle incident on crystal target emission. Light emitting diodes (LEDs) are the current lighting technology solution gaining a wide adoption in a variety of commercial applications. They are now the dominant new lighting in office, public and domestic application, in addition they have almost completely covered the automotive head lamp market and now they are finding their way into more sophisticated instruments such as solar simulators. The best commercial LED's efficiencies are now above 60% and they are the most energy saving solution available. However there is a fundamental issue undermining their performance when they are considered for high brightness lighting applications. To generate high emission intensities, LEDs need to be driven at high current densities at which point their efficiency suffers from a phenomenon described as the efficiency droop. The efficiency droop's origin is rooted in a variety of complex processes including; Auger recombination, overflow of carriers from rich potential minima and carrier leakage out of active region.1-8 So far the highest luminous efficacies reported on LEDs are based on driving them at low current densities on the order of >11 Acm −2 . 9,10 In contrast to LEDs, Laser Diodes (LDs) can operate at very high current densities without suffering from efficiency droop. 11,12 However currently the LD's overall efficiency is well below that of LEDs and their application in lighting will require radical packaging designs and arrangement of the laser diode and phosphor target assemblies. To be able to manipulate the emission spectrum of devices based on LD induced lighting (LDIL) the type of phosphor targets and the level of impurities constituting the phosphor target material will need to be studied and adjusted. Recent research has demonstrated the necessity of these studies by investigating the structural and thermal properties of Tb, Ce doped Y 3 Al 5 O 12 (YAG) single crystals. 13,14 The results act as pointers to the research that needs to be undertaken in parallel to both develop radical designs of LDIL modules and the associated single crystals used as emitting targets. In this report we have focused on studying different crystal sizes of the same phosphor material with the same LDs. We have carried out studies on beam incident angle and relationship between the emiss...

Single crystal CVD diamond has many desirable properties compared to current, well developed, detector materials; exceptional radiation, chemical and physical hardness, chemical inertness, low Z (close to human tissue, good for dosimetry), wide bandgap and an intrinsic pathway to fast neutron detection through the 12 C(n,α) 9 Be reaction. However effective exploitation of these properties requires development of a suitable metallisation scheme to give stable contacts for high temperature applications. To best utilise available processing techniques to optimise sensor response through geometry and conversion media configurations, a reliable model is required. This must assess the performance in terms of spectral response and overall efficiency as a function of detector and converter geometry. The same is also required for proper interpretation of experimental data. Sensors have been fabricated with varying metallisation schemes indented to permit high temperature operation; Present test results indicate that viable fabrication schemes for high temperature contacts have been developed and present modelling results, supported by preliminary data from partners indicate simulations provide a useful representation of response.

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