Effect of parasitics on electrochemical capacitance-voltage profiling of pseudomorphic high electron mobility transistor structures

Abstract

The effect of parasitic series resistances on electrochemical capacitance-voltage (EC-V) profiling is simulated numerically for AI~Ga 1 ~ks/In Ga 1 .As pseudomorphic high electron mobility transistor (p-HEMT) st-ructures. ~e actual EC-V measurement is simulated numerically by reconstructing the charge distribution from an intrinsic distribution calculated from a self-consistent k. p model. The calculated charge distribution then forms the basis for examining the possible profiles an EC-V measurement would produce when parasitics are taken into account. From a simple lumped-circuit model, it is shown that parasitic resistances distort the shape of the charge distribution by changing the relative heights of the 5-layer and channel charges. Hysteresis effects may also occur and may be accompanied by a change in material type from n to p even though the material is known to be n-type over the entire range of measurement. Additionally, an undesirable dependence of the charge profile on the probe signal frequency is found.

A comparative study for profiling ultrathin boron layers in Si

“…This could be due to transition of etching through the change in doping level as discussed in [14]. These distortions may also result from parasitic series resistance, which may originate from conduction through the partially depleted barrier layers or from the doped region as surface states are drawn closer to it through etching [15]. Lower measurement voltages cause discrepancies between two models.…”