Влияние условий роста и уровня легирования на кинетику люминесценции слоев Ge : Sb, выращенных на кремнии

Light-emitting properties of Ge-on-Si(001) layers doped by Sb were studied by stationary and time-resolved photoluminescence (PL) at room temperature. It was obtained that the PL intensity of n-Ge/Si(001) structures is maximized when the doping level is close to the equilibrium solubility of Sb in Ge (~1019 cm-3) which is in accordance with the previously published data. Time-resolved studies of the direct-related PL signal have shown that both the donor density and the growth conditions of doped layer, in particular, the growth temperature influence the PL kinetics. It was obtained that the increase of doping level leads to the decrease of the characteristic carrier lifetime. Moreover, usage of low growth temperatures which is needed to form the doped n-Ge layers also results in shortening of the carrier lifetime as compared with Ge layers grown at high temperatures. It was found that rapid thermal anneal at proper conditions could partially compensate the above mentioned detrimental effects and lead to the increase of both the PL intensity and carrier lifetime.

Hydrogen-Induced Damage During the Plasma Etching Process

As devices scale down, we need to employ higher ion energy in the plasma etching to meet the requirements for critical dimensions. As a result, physical damage can be more severe. Since hydrogen can penetrate deeply into silicon due to its low mass compared to other species, there is a possibility of electrical degradation by deeply penetrated hydrogen. In this study, we demonstrated hydrogen-induced damage from the plasma etching process. Permeated hydrogen from the plasma etching process increases the amount of interface and bulk defects with increasing bias power, resulting in electrical degradation. Improvement of the device performance was possible via process modification using a rapid thermal anneal (RTA) directly after the hydrogen-containing plasma etching process and the hydrogen-free etching process.