Cluster-eliminating filter for depositing cluster-free a-Si:H films by plasma chemical vapor deposition

Abstract

A cluster-eliminating filter is developed to reduce a volume fraction VF of amorphous silicon nanoparticles above approximately 1 nm in size (referred to as a cluster) incorporated into a-Si:H films. The filter reduces the VF value by using the difference between a sticking probability of clusters and a surface reaction probability of SiH3 radicals, which are the predominant deposition radicals. By employing the filter together with a cluster-suppressed plasma chemical vapor deposition reactor, the VF value is reduced below 1∕180 compared to that for the conventional device quality films. Such cluster-free a-Si:H films have an extremely small hydrogen concentration associated with Si-H2 bonds below 5.46×10−3at.%.

Deposition of cluster-free P-doped A-Si:H films using a multi-hollow discharge plasma CVD method

“…Reducing incorporation of amorphous silicon particles (clusters) in a size range below 10nm into a-Si: H films is important for realizing highly stable a-Si: H solar cells of high efficiency [1][2][3]. Recently, we have successfully deposited cluster-free a-Si: H films of 4.7x10 15 cm-3 in stabilized defect density at a rate of 3.0nm/s using a multi hollow discharge plasma CVD method [4).…”

Real-time mass measurement of dust particles deposited on vessel wall in a divertor simulator using quartz crystal microbalances

“…The slits of one plate were covered by the other plate as shown in Fig. 2 [12]. The gap is much smaller than the mean free path of radicals and nanoparticles.…”

“…where T p is the transmittance of each plate (T p = 0.4) and b is the surface loss probability of radicals [12]. b of hydrocarbon radicals depends on the species: b (C 2 H) = 0.80 ± 0.05, b (C 2 H 3 ) = 0.35 ± 0.1 and b (CH 3 , C 2 H 5 ) = 10 À3 on surface without ion bombardment at room temperature and b also depends on the temperature of depositional surface [19].…”

“…The divertor simulator can simulate carbon dust formation in the divertor region of LHD [7][8][9][10][11]. We are developing a dust monitoring method using quartz crystal microbalances (QCMs) equipped with a dust eliminating filter [12]. QCMs have been successfully employed in some fusion devices as in situ diagnostics for measurement of re-deposited layers [13,14].…”

Deposition of cluster‐free P‐doped a‐Si:H films using SiH4+PH3 multi‐hollow discharge plasma CVD

“…Lower volume fraction of clusters in films shows lower concentration of Si-H 2 bonds in films [7], which are responsible for lightinduced degradation of the films [8]. Reducing the incorporation of clusters is important for realizing highly stable a-Si:H solar cells with high efficiency [7,9,10].…”