An ultrasonic transducer that can include a driver side and a bias voltage side. In the method, the server detects one or more unpaired message which are stored in a data structure on the server. The impurity atom is a faster diffusing species relative to silicon atoms. A detector may enable the current source in response to detecting a defined steady-state condition of the LO clock signal, and may disable the current source in response to the completion of the first signal. Then an opening is formed through the rear passivation layer to the first doped region; and electrical contacts are formed on the rear surface to electrically connect to the first and second doped regions.