Analysis of quantum levels for self‐assembled InGaAsN/GaP quantum dots

Abstract

We develop the design method of luminescence device with the strained quantum dots (QDs) on Si using a theoretical analysis on realistic structure. We have calculated numerically the first electron and heavy‐hole quantum levels of self‐assembled InGaAsN/GaP QDs using the finite element method, the model‐solid theory and the band‐anticrossing model. The calculation results indicate that N incorporation into InGaAs QDs drastically reduces the conduction band minimum (∼120 meV/N at%), and that it is shown enough energy difference between the first electron‐quantum level and GaP X‐state when N composition is 1∼2%. For self‐assembled In0.5Ga0.5As0.99N0.01/GaP QDs, the calculated transition energy at room temperature (RT) nearly matches with the measured photoluminescence (PL) peak energy. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Strain-induced fundamental optical transition in (In,Ga)As/GaP quantum dots

“…We clearly see that the band alignment should favour a strongly confined HH state inside the QD, as predicted in previous theoretical studies. 16,18 Concerning the conduction valleys, the C potential is found to be well above the X potentials which confirms the impossibility of obtaining a C-type ground electron state inside the QD in the low In content range. 16 The case of X valleys is the most interesting.…”

“…First, Fukami et al have calculated the heavy hole (HH) and electron quantum levels at the C point with a simple model-solid theory approach and pointed out the proximity of the C electron confined state with the X conduction band of GaP. 18 This result was refined by calculating the first HH and electron state at the C point with an eight band kÁp model. 16,19 In addition, the positions of the first confined states in the X and L valleys were deduced from an extended spds tight-binding (TB) model assuming a QW with a thickness equal to the height of the QD and disregarding the possible mixing between C,X,andLvalleys.…”

Effect of the nitrogen incorporation and fast carrier dynamics in (In,Ga)AsN/GaP self-assembled quantum dots

“…2), may be attributed to different band lineups, strain status, or quantum confinement. 15 But this could also be explained by the appearance of structural defects leading to non-radiative recombinations when nitrogen is introduced. In the case of nitrogen-free (In,Ga)As QDs, a double peak structure is observed at low temperature.…”

“…14 Finally, Fukami et al predicted a direct bandgap optical transition up to 1100 nm using a 50% In composition and an N composition between 1% and 2% with the Band Anti-Crossing model. 15 In these works, the QDs photoluminescence efficiency comparison with nitrogenfree (In,Ga)As/GaP QDs was not addressed. Furthermore, the experimental determination of carrier dynamics on the different QDs energy levels was not measured, which is a crucial information for further device developments.…”

Electronic wave functions and optical transitions in (In,Ga)As/GaP quantum dots

“…Meanwhile, structural properties of these QDs were investigated at a large scale in terms of size and density [20,[26][27][28] and at the atomic scale through transmission electron microscopy (TEM), planview, and cross-sectional scanning tunneling microscopy (STM) [29][30][31][32], revealing a complex and inhomogeneous indium incorporation behavior inside the QDs. Fukami et al first noticed in their pioneering works the vicinity of the conduction band minimum in the QD and the X valley of GaP with a simple model-solid theory approach [33]. The description of the electronic structure of (In,Ga)As/GaP QDs was then refined using a mixed eight-band kp/tight-binding (TB) spds* methodology [27,29].…”