5.1.2.8 Comparison to Measurements

Since almost all available measurements of gate leakage in MOS devices are performed on turned-off MOS transistors, a comparison with measurements will be given before turned-on devices are investigated in Section 5.1.4. The TSU-ESAKI model with an analytical WKB transmission coefficient is in good agreement with recently reported data for devices with different gate lengths and bulk doping [249,96] as shown in Fig. 5.10 for nMOS (left) and pMOS devices (right) [255]. It can be seen that the gate current density can be reproduced over a wide range of dielectric thicknesses with a single set of physical parameters. Additional measurements have been performed on MOSFETs with a gate dielectric thickness of 1.5nm (see the lower part of Fig. 5.10) and compared with the results of other simulators (UTQUANT [256] and MEDICI [257]). Under inversion condition the fit is not perfect while under accumulation the measurements can be reproduced well. Note that with UTQUANT, the low-bias tunneling current cannot be reproduced and MEDICI completely failed for the pMOS device.

Figure 5.10: Comparison of simulations using different simulators with measurements of nMOS (left) and pMOS (right) devices [249,96,255].

A. Gehring: Simulation of Tunneling in Semiconductor Devices