the laser that is used is typically a tripled yag or excimer laser with a spot size of 50 u03bcm to 500 u03bcm a pulse width of 3 to 50 nanoseconds and a total fluence of between 300 mj and 500 mj per pulse as the first layer is under thermal stress it is often advantageous to use an auxiliary heating mechanism such as a hot plate to keep the wafer at an intermediate to high temperature during this process for example if the layer is grown at 1000 u00b0 c heating the wafer to 500 u00b0 c during the laser process reduces the thermal stress approximately by half reducing the film 39 s tendency to crack the wafer is loaded into the growth system in step 609 and the growth of the second gan layer 506 is done in step 610 thickness of this layer is preferably between 50 and 500 microns more preferably 300 microns the growth conditions for this layer may be the same as those used for the first layer or they may differ in terms of growth rate gas flows partial pressures of precursor gases composition of material deposited temperature etc layers 502 and 506 merge to form composite layer 507 in step 611 the wafer is cooled once again and removed from the growth system although the total combined thickness of composite layer.