Interface Properties of GaP/Si Heterojunction Fabricated by PE-ALD

Alexander S. Gudovskikh (1) , Alexander Uvarov (1) , Ivan A. Morozov (1) , Artem Baranov (1) , Dimitry Kudryashov (1) , Kirill S. Zelentsov (1) , Alexandre Jaffré (2) , Sylvain Le Gall (2) , Arouna Darga (2) , Aurore Brézard-Oudot (2) , Jean-Paul Kleider (2)

1 SPBU - Saint Petersburg University
2 GeePs - Laboratoire Génie électrique et électronique de Paris

The properties of n‐GaP/p‐Si interface as well as their influence on solar cell performance are studied for GaP layers grown by low‐temperature (380 °C) plasma‐enhanced atomic layer deposition (PE‐ALD). The influence of different plasma treatments and RF power values are explored. The increase of RF power leads to a growth transition from amorphous (a‐GaP) to microcrystalline GaP (μc‐GaP) with either amorphous‐GaP/Si or epitaxial‐GaP/Si interface, respectively. However, when continuous hydrogen plasma is used the amorphous‐GaP/Si interface exhibits better photovoltaic performance compared to the epitaxial one. Values of open circuit voltage, Voc = 0.45–0.55 V and internal quantum efficiencies, IQE > 0.9 are obtained for amorphous‐GaP/Si interfaces compared to Voc = 0.25–0.35 V and IQE < 0.45 for epitaxial‐GaP/Si interfaces. According to admittance spectroscopy and TEM studies the near‐surface (30–50 nm) area of the Si substrate is damaged during growth with high RF power of hydrogen plasma. A hole trap at the level of EV + (0.33 ± 0.02) eV is detected by admittance spectroscopy in this damaged Si area. The damage of Si is not observed by TEM when the deposition of the structures with epitaxial‐GaP/Si interface is realized by a modified process without hydrogen plasma indicating that the damage of the near‐surface area of Si is related to hydrogen plasma interaction.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Alexander S. Gudovskikh, Alexander Uvarov, Ivan A. Morozov, Artem Baranov, Dimitry Kudryashov, et al.. Interface Properties of GaP/Si Heterojunction Fabricated by PE-ALD. physica status solidi (a), 2019, 216 (10), pp.1800617. ⟨10.1002/pssa.201800617⟩. ⟨hal-01943257⟩