Density of states in the gap of CdTe:V deduced from the modulated photocurrent technique

Investigation of bandgap states using the modulated photocurrent technique in both high and low frequency regimes

“…The MPC technique has been used to study the DOS in many kinds of semiconductors and in both the coplanar and the sandwich configuration [8][9][10][11][12][13][14][15][16]. All these works make use of the HF regime.…”

The role of the recombination centers on the modulated photocurrent: Determination of the gap state parameters of semiconductors

“…The modulated photocurrent (MPC) technique has been applied to determine the density of states (DOS) in the energy gap of various semiconductors including crystalline [1][2][3], amorphous [4][5][6][7][8][9][10], microcrystalline [11], quasicrystalline [12] as well as organic [13,14] semiconductors. This technique is very powerful as it can reveal even very low trap densities, as well as the capture coefficients.…”

The modulated photocurrent technique: a powerful tool to investigate band gap states in silicon based thin films

“…This is however not due to different species of traps, but rather to the peculiar shape of the DOS, the high frequency points beginning to explore the conduction band tail, thus leading to an increase of sin(φ)×qG ac /I ac as suggested by Eq. (6). The check that the onset of this second step at high frequency is not due to different species of traps is that the curves corresponding to different dc generation rates do not exhibit any shift in frequency of this step, but rather converge, as expected from the HF analysis.…”

“…The same kind of relation holds for holes, replacing all electron quantities by the corresponding hole quantities in Eq. (6). Therefore, the electron and hole contributions to the modulated photocurrent in the HF regime are actually sensitive to the cN/µ ratios rather than to the DOS itself.…”

“…It has been used in a wide variety of crystalline semiconductors [4][5][6], quasicrystals [7] and organic semiconductors [8], but the main use concerned disordered semiconductors. This includes chalcogenides [9,10], hydrogenated amorphous silicon (a-Si:H) [11][12][13][14][15][16][17][18][19][20], silicon based alloys like amorphous silicon nitride and silicon carbide [21,22] and silicon-germanium [23,24].…”