Role of conduction-band filling in the dependence of InN photoluminescence on hydrostatic pressure

We present an experimental and theoretical study of the role of band filling effects in the hydrostatic pressure dependence of photoluminescence (PL) from InN. The PL peak pressure coefficient $d{E}_{\mathrm{PL}}∕dp$ is shown to decrease from $27.3\ifmmode\pm\else\textpm\fi{}1.1\phantom{\rule{0.3em}{0ex}}\mathrm{meV}∕\mathrm{GPa}\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}20.8\ifmmode\pm\else\textpm\fi{}0.8\phantom{\rule{0.3em}{0ex}}\mathrm{meV}∕\mathrm{GPa}$ when the electron concentration increases from $3.6\ifmmode\times\else\texttimes\fi{}{10}^{17}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}1.1\ifmmode\times\else\texttimes\fi{}{10}^{19}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$. We argue that this decrease is caused by the pressure sensitivity of the Fermi level in InN, which induces a lowering of $d{E}_{\mathrm{PL}}∕dp$ with respect to the band gap pressure coefficient $d{E}_{G}∕dp$. $d{E}_{\mathrm{PL}}∕dp$ is shown to depend on the electron concentration in accordance with predictions based on ab initio calculations, taking into account the influence of conduction-band nonparabolicity.