3.7 The CV measurement (DLTS)

 

The CV measurements can be realised by either the Laplace system hardware or by the external CV (LCR) meter. The list of hardware supported is given in a previous chapter. If the Laplace system is initialised on the Main screen then it is not necessary to initialise the hardware for performing the CV measurement with the Laplace system hardware. If the external meter is chosen on the Hardware menu then this hardware needs additional initialisation. The external meter is configured on the Hardware window accessed from the Main window. On the top menu there are buttons allowing the CV curve to be redrawn in different ways which are used for, e.g. the pn junction profiling. When the measurement starts the sample area and the dielectric constant defined for the current sample in the data base are taken and written in to the corresponding text boxes. When the measurement is completed these values can be changed. The results when saved are also put in the currently open data base.

 

When the Start from and return to 0V check box is unchecked then to the sample the current start voltage is applied and when the measurement is completed the end voltage bias is maintained. These values are shown in a separate text box. Note: which voltage is the starting one and which is the ending one is defined whether the Up check box is checked. This utility allows measuring, e.g., the CV curve hysteresis.