Atmospheric Pressure Chemical Vapour Deposition of 3C-SiC for Silicon Thin-Film Solar Cells on Various Substrates

Abstract

The production of crystalline silicon thin-film solar cells on cost effective ceramic substrates depends on a highly reliable diffusion barrier to separate the light absorbing layers from the substrate. Ideally this intermediate layer should be deposited with cost effective techniques, be conductive and should feature optical confinement. Furthermore the intermediate layer should withstand high temperatures and harsh chemical environments like they occur during solar cell processing. Especially stability against oxidizing solvents like HNO3 or inactivity during e.g., oxide removing steps with HF is required. Crystalline silicon carbide (c-SiC) deposited by atmospheric pressure chemical vapour deposition (APCVD) can match all those requirements and additionally fits the thermal properties of crystalline silicon. The c-SiC intermediate layer is deposited from methyltrichlorosilane (MTS) and H2 at 1100 degrees C. Under these conditions, growth of solely cubic 3C-SiC could be observed by X-ray diffraction measurements. Use of such intermediate layers during high temperature steps prevents diffusion of transition metals, originating from the substrates, into active silicon layers. Doping of these 3C-SiC layers with nitrogen results in specific resistivity of less than 100 ohms cm. The different potentially cost-effective substrates are made from graphite, crystalline silicon, sintered silicon carbide and sintered zircon (ZrSiO4). Surface properties of the coated substrates were investigated, explaining changes in surface roughness and influences on the solar cell processing.

Monolithic Si nanocrystal/crystalline Si tandem cells involving Si nanocrystals in SiC

“…The total boron dose in this emitter is extremely high in order to ensure that neither the emitter nor the n+ SiC/p+ Si TRJ is destroyed by subsequent high‐temperature processing. Next, polycrystalline n+ SiC with a grain size of about 100 nm was deposited by atmospheric pressure chemical vapour deposition using methyltrichlorosilane, hydrogen and nitrogen at 1100 °C . Samples are heated to 1100 °C under B 2 H 6 and cooled under N 2 to maintain the high doping concentrations at the sample surface.…”

Progresses in Synthesis and Application of SiC Films: From CVD to ALD and from MEMS to NEMS

“…CVD of SiC films has been carried out by decomposing several organic or organometallic compounds in the most varied types of designed reactors. In the case of APCVD, methyltrichlorosilane (MTS, CH 3 SiCl 3 ) is the single-source precursor most often used in SiC film synthesis, not only due to the stoichiometry of silicon (Si) and carbon (C) in its molecular structure, but also due to the fact that good quality films are obtained [ 29 , 30 , 31 ]. Another single-source precursor recently used is the hexamethyldisilane (HMDS, Si 2 C 6 H 18 ) [ 32 ].…”

“…As dual-source precursors are used in APCVD, we can cite the mixture of propane (C 3 H 8 ) and silane (SiH 4 ) [ 33 ] or dichlorosilane (DCS, SiH 2 Cl 2 ) and trichlorosilane (HCl 3 Si) [ 34 ]. For both cases, a high-purity hydrogen and argon mixture is used as a carrier gas [ 30 ].…”

“…SiC growth rates reported in this kind of CVD reactor are of up to several μm/min [ 33 , 34 ], with the possibility of performing the film doping process with materials of type n or p [ 34 ]. We can cite as n-type material used in APCVD SiC as the nitrogen [ 36 ] and as p-type material as the boron [ 30 ]. In the literature, it is reported that both 3C-SiC epitaxial and polycrystalline films have been deposited by the APCVD technique.…”

Recrystallized silicon thin-film solar cells on zircon ceramics

“…The detailed process 27, 79104 Freiburg, Germany thickening, such films can be used to make solar cells REPARATION substrates were lasered to sizes of mm² and cleaned using acetone and 2-propanol to remove possible organic residues. A surface cleaning for , as the bulk contamination is Ωcm p-type, mc-Si substrates amples were encapsulated with 10 µm of crystalline 1100°C and 1 atm from ) and hydrogen [4]. Some samples were additionally coated with 1 µm of SiO 2 on one to increase the reflectivity at the back and improve optical recrystallized silicon thin-films followed by the deposition of 5 µm high purity, Si deposited from trichlorosilane (HSiCl 3 ).…”