Capture-emission process in double Poole-Frenkel well traps: Theory and experiments

The field-dependent capture-emission process has been studied for double Poole-Frenkel well traps compared with that of single Poole-Frenkel well trap. The emission rate increases with increasing field strength for a single trap. However, for a double trap, it increases to a maximum then decreases with further increasing field due to the barrier lowering and interstate interactions between these two wells. Experimental capacitance deep-level transient spectroscopic data of GaAs samples grown by molecular-beam epitaxy show that when there is a delay in the capacitance transient then there always appear two levels, namely, 0.4 and 0.5 eV. In addition, for both levels, the emission rate increases first to a maximum and then decreases with increasing electric field.