Electron and hole injection barriers between silicon substrate and RF magnetron sputtered In2O3 : Er films

In2O3 : Er films have been synthesized on silicon substrates by RF magnetron sputter deposition. The currents through the synthesized metal/oxide/semiconductor (MOS) structures (Si/In2O3 : Er/In-contact) have been measured for n and p type conductivity silicon substrates and described within the model of majority carrier thermoemission through the barrier, with bias voltage correction to the silicon potential drop. The electron and hole injection barriers between the silicon substrate and the film have been found to be 0.14 and 0.3 eV, respectively, by measuring the temperature dependence of the forward current at a low sub-barrier bias. The resulting low hole injection barrier is accounted for by the presence of defect state density spreading from the valence band edge into the In2O3 : Er band gap to form a hole conduction channel. The presence of defect state density in the In2O3 : Er band gap is confirmed by photoluminescence data in the respective energy range 1.55–3.0 eV. The band structure of the Si/In2O3 : Er heterojunction has been analyzed. The energy gap between the In2O3 : Er conduction band electrons and the band gap conduction channel holes has been estimated to be 1.56 eV

Electron and hole injection barriers between silicon substrate and RF magnetron sputtered In2O3 : Er films

In2O3 : Er films have been synthesized on silicon substrates by RF magnetron sputter deposition. The currents through the synthesized metal/oxide/semiconductor (MOS) structures (Si/In2O3 : Er/In-contact) have been measured for n and p type conductivity silicon substrates and described within the model of majority carrier thermoemission through the barrier, with bias voltage correction to the silicon potential drop. The electron and hole injection barriers between the silicon substrate and the film have been found to be 0.14 and 0.3 eV, respectively, by measuring the temperature dependence of the forward current at a low sub-barrier bias. The resulting low hole injection barrier is accounted for by the presence of defect state density spreading from the valence band edge into the In2O3 : Er band gap to form a hole conduction channel. The presence of defect state density in the In2O3 : Er band gap is confirmed by photoluminescence data in the respective energy range 1.55–3.0 eV. The band structure of the Si/In2O3 : Er heterojunction has been analyzed. The energy gap between the In2O3 : Er conduction band electrons and the band gap conduction channel holes has been estimated to be 1.56 eV

Region 1.2 of the RNA polymerase σ subunit controls recognition of the −10 promoter element

Recognition of the −10 promoter consensus element by region 2 of the bacterial RNA polymerase σ subunit is a key step in transcription initiation. σ also functions as an elongation factor, inducing transcription pausing by interacting with transcribed DNA non-template strand sequences that are similar to the −10 element sequence. Here, we show that the region 1.2 of Escherichia coli σ(70), whose function was heretofore unknown, is strictly required for efficient recognition of the non-template strand of −10-like pause-inducing DNA sequence by σ region 2, and for σ-dependent promoter-proximal pausing. Recognition of the fork-junction promoter DNA by RNA polymerase holoenzyme also requires σ region 1.2 and thus resembles the pause-inducing sequence recognition. Our results, together with available structural data, support a model where σ region 1.2 acts as a core RNA polymerase-dependent allosteric switch that modulates non-template DNA strand recognition by σ region 2 during transcription initiation and elongation