Influence of PE‐ALD of GaP on the Silicon Wafers Quality

An attractive method of low‐temperature plasma‐enhanced atomic layer deposition (PE‐ALD) of GaP on silicon wafer was recently proposed. In the present paper, the influence of the growth process on the quality of silicon wafers is explored by space charge capacitance techniques, C–V profiling and deep level transient spectroscopy (DLTS). No DLTS peak is observed for PE‐ALD GaP deposited onto n‐type wafer, meaning that the defect concentration is very low (less than 1 × 1012 cm−3) and that the growth process does not affect the properties of the n‐Si wafer. For boron‐doped p‐type silicon, C–V profiling shows that there is no deactivation of boron doping after the PE‐ALD process, as could have been expected from the presence of hydrogen in the plasma. Measurements on the reference Schottky diodes formed on the p‐type Si wafer reveal the presence of the well‐known Fe interstitial defects at the position EV + 0.38 eV with a concentration of 3 × 1013 cm−3. PE‐ALD of GaP leads to a modification of the response of this defect and to the appearance of another response in the low temperature range, possibly related to changes in the Fe interstitial defect environment or configuration. However, deep‐levels were not detected in p‐Si after PE‐ALD, meaning that the quality of p‐Si does not degrade. Low‐temperature plasma‐enhanced atomic layer deposition is a perspective method for fabrication of multi‐junction solar cells on silicon wafers. According to DLTS measurements, it does not lead to deep level formation in n‐ and p‐type wafers after growth of GaP at temperature below 400 °C. The boron deactivation by hydrogen is not observed in p‐Si for used growth conditions.