Transport properties for different bubbler designs [MOVPE]

In the MOVPE process a steady, controllable flux of precursor into the reaction chamber is a key factor when fabricating highly complex device structures employing ternary and quaternary layers. Historically a simple bubbler design has been employed to perform this task with carrier gas flow and source temperature control able to provide a suitably stable system. However, with the increasing volume demands placed on MOVPE equipment, increased flows and larger bubblers have become necessary and the simple dip tube (dip leg) approach is no longer 100% suitable. In this study, an investigation of 3 novel bubbler dip tube designs have been performed and a comparison made with the standard approach. An Epison III ultrasonic analyser was employed to monitor the pick up of the precursor from a variety of bubblers across a range of flow rates and temperatures. Flows up to 10 sclm have been investigated and differences observed between bubbler dip leg designs the results of which highlight the improvements achievable using a new crosspiece dip tube design.