Simple microcomputer-based apparatus for combined DLTS–C-V measurement

A very simple high-performance microcomputer-based apparatus for the combination of DLTS and C-V curve measurements is reported here. This apparatus has an A/D converter instead of gated boxcar integrators and a D/A converter instead of a pulse generator, both of which are controlled by an eight-bit microcomputer. An analog feedback loop for CCDLTS is replaced by a digital control loop which does not appear in hardware. This has been done by developing an adaptive feedback gain control algorithm for the control program of the microcomputer. All data required for DLTS analyses such as the determination of energy levels, thermal emission rates, and in-depth profiles of deep traps can be obtained in a single temperature scan using the multipoint measurements of the capacitance transient (DLTS mode) performed repetitively with different filling pulse voltages. The acquisition capacity of this apparatus in a single temperature scan is about 50 times higher than that of a conventional one, which uses double boxcar integrators. In addition, C-V curve measurements (C-V mode) can be done in DLTS mode in 20 K intervals.