Low temperature in situ boron doped Si epitaxial growth by ultrahigh vacuum electron cyclotron resonance chemical vapor deposition Plasma enhanced selective area microcrystalline silicon deposition on hydrogenated amorphous silicon: Surface modification for controlled nucleation Investigation of substrate-dependent nucleation of plasma-deposited microcrystalline silicon on glass and silicon substrates using atomic force microscopy A new technique for semiconductor epitaxy at low substrate temperatures is presented, called low-energy dc plasma enhanced chemical vapor deposition. The method has been applied to Si homoepitaxy at substrate temperatures between 400 and 600°C and growth rates between 0.1 and 1 nm/s, using silane as the reactive gas. The quality of the Si films has been examined by reflection high-energy electron diffraction, scanning tunneling microscopy, cross-section transmission electron microscopy, and high-resolution x-ray diffraction. Two effects have been identified to lead to the formation of stacking faults after an initial layer of defect-free growth: ͑1͒ substrate bombardment by ions with energies in excess of 15 eV, and ͑2͒ hydrogen adsorption limiting the surface mobility of Si atoms and silane radicals. Both result in the accumulation of surface roughness, facilitating the nucleation of stacking faults when the roughness reaches a critical level. Defect introduction can be eliminated effectively by biasing the substrate during growth and by decreasing the hydrogen coverage, either by admixing small amounts of germane to the silane or by using a sufficiently high plasma density.

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Low energy plasma enhanced chemical vapor deposition (LEPECVD) has been applied to the synthesis of Si-modulation doped field effect transistor structures, comprising a SiGe relaxed buffer layer and a modulation doped strained Si channel. A growth rate of at least 5 nm/s for the relaxed SiGe buffer layer is well above that obtainable by any other technique. Due to the low ion energies involved in LEPECVD, ion damage is absent, despite a huge plasma density. The structural quality of the LEPECVD grown SiGe buffer layers is comparable to that of state-of-the-art material. The electronic properties of the material were evaluated by growing modulation doped Si quantum wells on the buffer layers. We obtain a low temperature (2 K) Hall mobility of μH=2.5×104 cm2/Vs for the electrons in the Si channel at an electron sheet density of ns=8.6×1011 cm−2.

We report on effective hole mobility in SiGe-based metal–oxide–semiconductor (MOS) field-effect transistors grown by low-energy plasma-enhanced chemical vapor deposition. The heterostructure layer stack consists of a strained Si0.17Ge0.83 alloy channel on a thick compositionally-graded Si0.52Ge0.48 buffer. Structural assessment was done by high resolution x-ray diffraction. Maximum effective hole mobilities of 760 and 4400 cm2/Vs have been measured at 300 and 77 K, respectively. These values exceed the hole mobility in a conventional Si p-MOS device by a factor of 4 and reach the mobility data of conventional Si n-MOS transistors.

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