外电场作用下氮化物有限抛物量子阱中激子的极化子效应

Polaron Effects of an Exciton in Nitride Finite Parabolic Quantum Well in an Electric Field

考虑GaN/Al_xGa_(1-x)N有限抛物量子阱(PQW)中空穴有效质量及声子模的各向异性,采用LLP变分法计算了外电场作用下有限PQW中激子的能量。结果表明,轻、重空穴激子的基态能随阱宽的减小而增大,结合能随着阱宽的减小,先增大后减小;考虑极化子效应时,结合能有明显的降低;轻空穴激子的结合能和基态能量均比重空穴激子的高;闪锌矿阱中激子的基态能量比纤锌矿阱中的高,而闪锌矿阱中激子的结合能比纤锌矿阱中的低;有外电场作用时,激子的结合能和基态能量降低较明显。

With the anisotropy of optical phonon modes and the band mass of the holes in a GaN/AlxGa1-xN finite parabolicquantum well （PQW） taken into account, the energy of an exciton in a GaN/AlxGa1-xN PQW in an electric field iscalculated in a LLP variational method. The results show as follows. The ground state energy of a heavy-hole exciton or alight-hole exciton in a PQW increases when the width of the wells decreases while the binding energy of a heavy-holeexciton or a light-hole exciton in a PQW increases first and then decreases with the decrease of the width of PQW. In termsof the effect of polaron, the binding energy of an exciton is significantly smaller than the results of a bare exciton. Theground state energy and binding energy of a light-hole exciton are larger than the corresponding values of a heavy-holeexciton. The ground state energy of an exciton in a Zinc blende PQW is larger than the results of a wurtzite PQW. Thebinding energy of an exciton in a Zinc blende PQW is less than the results of a wurtzite PQW. The ground state energy andbinding energy of an exciton in an electric field are significantly less than the results of an exciton without a electric field.