Hydrogen-induced platelets in silicon: Infrared absorption and Raman scattering

Abstract

The local vibrational modes of hydrogen-induced platelets in crystalline silicon have been studied using infrared absorption and Raman-scattering spectroscopy. Four overlapping but distinct bands are observed in the region 2000-2200 cm . Hydrogen-isotope substitution confirms that these are hydrogenrelated stretching vibrations. Hydrogen concentrations obtained from the integrated infrared band intensities are comparable to total hydrogen concentrations obtained from secondary-ion mass spectroscopy. Relative intensities of the bands depend on sample history and can be varied by annealing. This indicates that the four bands arise from at least three distinct structures. Polarization-sensitive Raman measurements indicate that the Raman-active local modes transform according to the fully symmetric representation of a trigonal point group. One structure possesses distinct ir and Raman-active local modes. We conclude that the platelets are highly ordered structures with fundamental building blocks consisting of silicon atoms with one hydrogen-saturated bond, and that at least one inversion-symmetric structure exists. We compare our results with previously proposed structures.

Hydrogen molecules and hydrogen-related defects in crystalline silicon

“…Heyman et al reported local vibrational modes of hydrogen-induced platelets at 2065, 2095, and 2125 cm Ϫ1 in crystalline silicon after plasma hydrogenation. 6 The peak wave numbers of the two components in the present study are in agreement with the theoretical and experimental ͑2095 and 2125 cm Ϫ1 ͒ values. However, the thermal stability of the two peaks is different in the present study: the peak at 2100 cm Ϫ1 persists for hydrogenation up to 500°C, while that at 2130 cm Ϫ1 vanishes for a hydrogenation temperature above 250°C.…”

“…1 An infrared-absorption experiment has shown that hydrogen introduced in to p-or n-type silicon forms complexes with acceptor or donor atoms. 2 Other experimental results and theoretical calculations have suggested that ͕111͖ platelets [3][4][5][6][7][8] and a metastable diatomic hydrogen complex [9][10][11] are formed in heavily doped n-type silicon.…”

First-principles calculations on the structure of hydrogen aggregates in silicon and diamond

“…In defect-free silicon the H 2 molecule at the tetrahedral interstitial site is the stable configuration [3][4][5]. The metastable configuration is the H Hydrogen introduced in high concentrations generates extended planar defects in silicon, lying along (111) and (100) crystallographic planes, that are called hydrogen-induced platelets (HIP) [6][7][8][9][10][11][12][13]. The platelets are located at depths corresponding to the maximum hydrogen concentration near the surface of the Si samples.…”

“…This phenomenon is the basis of the technologically important SmartCut TM process of obtaining high-quality silicon-on-insulator (SOI) layers [14]. Spectroscopic investigations showed that platelets contain Si-H bonds [6,[11][12][13] and, at T > 200…”

Optimization of the Ion-Cut Process in Si and SiC

“…The chemical activity and high diffusivity of hydrogen in Si cause it to quickly become bound by the ion-induced displacement damage to form a variety of defect complexes [4]. Thermal evolution leads to the formation of progressively more complex, hydrogenated defects such as the platelet [5], which plays an important role in the ion-cutting process. It consists of extended, hydrogen-terminated internal surfaces along either (100) or (111).…”