液封坩埚下降法生长非掺杂InP单晶的特性研究

用液封坩埚下降(LE-VB)法沿〈100〉晶向成功地生长了非掺杂InP单晶。LE-VB晶体的4.2K光致发光谱包含束缚于中性浅受主上的激子发光、与Zn受主相关的施主-受主(DA)对发光及其声子伴线、以及与本征缺陷等有关的深能级发光三部分。通过与液封直拉(LEC)生长的籽晶的光致发光谱比较表明,在LE-VB晶体中,束缚于中性浅受主上的激子发光与籽晶中的相差不大;DA对发光的晶格弛豫比籽晶中的小;与本征缺陷等有关的深能级发光强度比籽晶中的弱。晶体的室温光致发光谱仅包含带-带发光,其发光强度形貌测试结果表明,LE-VB晶体的带-带发光强度比LEC籽晶的强。用Huber法对晶片腐蚀的结果表明,在LE-BV晶体中,位错密度仅为LEC籽晶中的三分之一。分析认为,在LE-VB晶体中,本征缺陷和位错等浓度较低,可能是其带-带发光强度比在LEC籽晶中强的物理起因。

PROPERTIES OF UNDOPED BULK InP GROWN BY LIQUIDENCAPSULATED VERTICAL BRIDGMAN TECHNIQUE

Undoped bulk InP was grown along <100> direction by the liquid-encapsulated vertical Bridgman (LE-VB) technique. Photoluminescence spectra of as-grown InP at 4.2K were consisted of three parts. A peak exhibited near band gap energy is attributed to the recombination of bound excitons. At the low energy side of bound exciton (BE), a series of peaks with same energy interval are due to the recombination of donor-acceptor (DA) pairs with their phonon replicas, which are associated with Zn acceptor. A deep level recombination is characterized by a series of resolvable peak at its higher energy side, which can be associated with emission of native defects and their phonon replicas. The comparison results of the 4.2K PL spectra showed that in LE-VB crystsl the lattice relaxations of the DA emission are smaller and the PL intensities of the DL are stronger than those in the seed crystal grown by liquid-encapsulated czochralski (LEC)technique. At room temperature, only a band-to-band recombination was observable in both as-grown LE-VB crystal and LEC seed crystal. The PL mapping results showed that PL intensities of the band-to-band recombination in LE-VB crystal are stronger than those in LEC crystal. By combining the Huber etch pit density analysis, it is considered that the stronger PL intensities of the band-to-band recombination in LE-VB crystal can be due to the lower densities of the native defects responsible for the DL recombination and of the dislocations responsible for the Huber etch pit. The densities of the native defects and dislocations in the crystal can be reduced by LE-VB technique.