Charging energy spectrum of black phosphorus quantum dots

We present a theoretical study of the charging effects in single and double layer black phosphorus quantum dots (BPQDs) with lateral sizes of 2 nm and 3 nm. We demonstrate that the charging of BPQDs are able to store up to an N-max electron (that depends on the lateral size and number of layers in the QD), after which structural instabilities arises. For example, 3 nm wide hydrogen-passivated single layer BPQDs can hold a maximum of 16 electrons, and an additional electron causes the expelling of hydrogen atoms from the QD borders. We also calculated the addition energy (EA) spectrum. For single-layer QDs with 2 and 3 nm lateral sizes, the average EA is around 0.4 eV and 0.3 eV, respectively. For double layer QDs with the same sizes, the average EA is around 0.25 eV and 0.2 eV, respectively.