With the superior flux control of the Corrosive Series Valved Cracker, complex structures not possible with conventional thermally controlled sources can be achieved. Mixed Group V layers of varying compositions can be grown without the frequent recalibration procedures necessary when using standard sources. SIMS analysis of a continuously graded GaAs1-xSbx layer demonstrates the excellent flux control available when using two Group V valved crackers, with identical results achieved at two different growth rates.
The patented Veeco Corrosive Series Valved Cracker is the only proven all-PBN valved source available on the market today. This innovative technology offers valved flux control for reactive high-vapor pressure materials (such as antimony and tellurium) not compatible with the metal crucibles and valves of traditional valved sources. The source design utilizes an entire valve assembly, crucible and conductance tube constructed exclusively of pyrolytic boron nitride (PBN) to protect them from corrosion.
The valve assembly is removable, allowing easy loading of the large capacity crucible through the conductance tube. The crucible is heated to generate a beam flux. Gas flow is regulated through the PBN valve, providing rapid flux stabilization, quick shut-off and excellent reproducibility. In the cracking zone, a molecular flux may be thermally cracked to smaller molecular or atomic species. The source can also be operated in uncracked mode, if desired.
With recent enhancements, the Mark V Corrosive Series Valved Cracker incorporates a nozzle that provides excellent flux uniformity and reduced material waste. This improvement in material utilization results in:
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