Ke-Qing Lu

A model for the bandgap energy of the N-rich GaNAs(0 ≤ x ≤ 0.07)

A model for the bandgap energy of the N-rich GaNAs is developed. We find that the evolution of the conduction band minimum and the valence band maximum in the N-rich GaNAs is due to two factors. One is intraband coupling within the conduction band and separately within the valence band. The other one is the As level. It can pin the valence band maximum near the As level when the As content is large enough. It is also found that the character of the As impurity band is similar to the P impurity band in the N-rich GaNP.

A pressure dependence model for the band gap energy of the dilute nitride GaNP

The pressure dependence of the band gap energy of the dilute nitride GaNP is analyzed. It is found that the pressure dependence of the Г conduction band minimum (CBM) is stronger than that of the X CBM. We also find that the energy difference between the X CBM and the Г CBM in GaNP becomes large with increasing N content. In order to describe the pressure dependence of the band gap energy of the dilute nitride GaNP, a model is developed. Based on the model, we obtain the energy difference between the X CBM and the Г CBM in GaNP at standard atmospheric pressure. It agrees well with the results obtained by other method.

A Model Describing the Band Gap Energy of the Strained InxGa1−xNySbzAs1−y−z Alloy (0 < x ≤ 0.5, 0 < y ≤ 0.05, 0 < z ≤ 0.1)

The physical mechanism for the band gap evolution of the strained InxGa1−xNySbzAs1−y−z alloy is investigated. It is found that InxGa1−xNy SbzAs1−y−z alloy with small N and Sb contents can be considered as an alloy formed by adding N and Sb atoms in the host material InxGa1−xAs. Under this condition, the band gap evolution of InxGa1−xNySbzAs1−y−z is due to three factors. One is the intraband coupling interactions within the conduction band and separately within the valence band of the host material, another is the coupling interaction between the Sb level and the Г valence band maximum of the host material, and the other is the coupling interaction between the N level and the Г conduction band minimum of the host material. Based on the physical mechanism for the band gap evolution of InxGa1−xNySbzAs1−y−z, a model is developed. The model can describe the band gap energy of the strained InxGa1−xNySbzAs1−y−z alloy well.

Influence of In-N Clusters on Band Gap Energy of Dilute Nitride In x Ga1−x N y As1−y *

The In-N clusters form in the dilute nitride InxGa1−xNyAs1−y alloys after annealing. It is found that the formation of the In-N clusters not only raises the N levels lying above the conduction band minimum (CBM) of InGaAs, but also raises the N levels below the CBM of InGaAs, leading to the variation of the impurity-host interaction. The blueshift of the band gap energy is relative to the variation of the impurity-host interaction. In order to describe the blueshift of the band gap energy due to the formation of the In-N clusters, a model is developed. It is found that the model can describe the blueshift of the band gap energy well. In addition, it is found the blueshift of the band gap energy due to the atom interdiffusion at the interface can be larger than that due to the formation of the In-N clusters.

A model for the bandgap energy of the dilute nitride InGaNAs alloys by modifying simplified coherent potential approximation

In this paper, a model describing the bandgap energy of the dilute nitride alloy InxGa1-xNyAs1-y is developed based on the modification of simplified coherent potential approximation (MSCPA) and the band anti-crossing model (BAC). The parameters in the model are obtained by fitting the experimental bandgap energies of the ternary alloys InGaAs, InGaN, GaNAs and InNAs. It is found that the results agree well with the experimental data. We also find that although the bandgap energies of InxGa1-xNyAs1-y and InxGa1-xAs can be calculated by using MSCPA, the physical mechanisms for the bandgap evolution of InxGa1-xNyAs1-y and InxGa1-xAs are very different. In addition, it is found that the model in this work may be used in a larger composition range than the BAC model.

Pressure dependence of the band gap energy for the dilute nitride GaNxAs1−x

Abstract A model is developed to describe the pressure dependence of the band gap energy for the dilute nitride GaNxAs1–x. It is found that the sublinear pressure dependence of E− is due to the coupling interaction between E+ and E−. We have also found that GaNxAs1−x needs much larger pressure than GaAs to realize the transition from direct to indirect band gap. It is due to two factors. One is the coupling interaction between the E+ and E−. The other is that the energy difference between the X conduction band minimum (CBM) and the G CBM in GaNxAs1−x is larger than that in GaAs. In addition, we explain the phenomenon that the energy difference between the X CBM and the G CBM in GaNxAs1−x is larger than that in GaAs. It is due to the impurity-host interaction.

A model for the bandgap energy of the dilute nitride GaNxSb1−x (0 ≤ x ≤ 0.03)

A model for the bandgap energy of the dilute nitride GaNxSb1−x is developed. It is found that the bandgap reduction is due to two factors. One is the coupling interaction between the higher-lying N levels and the Γ conduction band minimum of GaSb. The other one is the lower-energy N impurity band. It can form the conduction band-edge of GaNxSb1−x. The bandgap reduction due to each factor is obtained. It is found that the bandgap reduction due to the former is much larger than that due to the latter.