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Interface Properties of GaP/Si Heterojunction Fabricated by PE‐ALD
Author(s) -
Gudovskikh Alexander S.,
Uvarov Alexander V.,
Morozov Ivan A.,
Baranov Artem I.,
Kudryashov Dmitry A.,
Zelentsov Kirill S.,
Jaffré Alexandre,
Le Gall Sylvain,
Darga Arouna,
BrezardOudot Aurore,
Kleider JeanPaul
Publication year - 2019
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201800617
Subject(s) - materials science , amorphous solid , heterojunction , epitaxy , band gap , analytical chemistry (journal) , substrate (aquarium) , optoelectronics , hydrogen , layer (electronics) , chemistry , nanotechnology , crystallography , oceanography , organic chemistry , chromatography , geology
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, V oc = 0.45–0.55 V and internal quantum efficiencies, IQE > 0.9 are obtained for amorphous‐GaP/Si interfaces compared to V oc = 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 E V + (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.