Defect Engineering in the Technology of Light-Emitting Structures Based on Monocrystalline Si Implanted with Rare Earth Ions

摘要

The possibilities of the suggested modification of the solid phase epitaxial technique for the engineering of structural defect and electrically and optically active center as well as for improvement of the properties of rare-earth doped Si-based light-emitting diodes (LEDs) have been demonstrated. TEM and X-ray diffraction revealed the presence of microtwins and dislocations in very high densities exceeding 10~(10) cm~(-2) in (111) Si:(Er,O). The changes in the spectrum of structural defects in (111) samples allowed us to observed some new effects and improve the characteristics of LEDs. On the basis of (111) structures, we have prepared avalanching and tunneling diodes (ADs and TDs). Saturation of the Er-related electroluminescence (EL) intensity in (111) ADs is achieved at current densities one order of magnitude lower than that in (100) TDs: under avalanche regime at 300 K, the effective cross section for excitation of Er~(3+) ions (σ) and the lifetime of the excited state is about four times higher than those values in (100) TDs. A weak temperature quenching of the EL intensity takes place in conventional (100) Si:(Er,O) diodes. In opposite, an enhancement of the Er-related EL intensity was observed in (111) ADs and TDs. The EL enhancement is related to the formation of deep level centers in the lower part of the forbidden gap. The study of the kinetics of the EL intensity when the reverse current is turned on shows that the same kind of Er-related light-emitting centers is introduced in (100) TDs as well as in (111) ADs and TDs. In (111) TDs, we have also observed the formation of a new kind of centers emitting under reverse bias. These centers are characterized by the highest σ. The main physical relationships established in defect formation and luminescence in (111) Si:(Er,O) samples allowed us to prepare the first LEDs with EL of Ho~(3+) ions at room temperature.