Study on yellow/green semiconductor laser diodes

我们研究了生长在InP衬底上的BeZnSeTe II-VI化合物半导体的Be组分对发光性能的影响，从而在绿光区域获得了明亮的发光。在此基础上，我们提出了一种MgSe/BeZnSeTe超晶格(SL)势垒层，将载流子和光场限制在BeZnSeTe有源层中，并改进了生长条件，如在SL界面进行锌辐照。基于这些结果，我们制作了发光器件。该器件由夹有MgSe/BeZnSeTe SL势垒层的BeZnSeTe量子阱有源层、MgSe/ZnCdSe SL n包层和MgSe/BeZnTe SL p包层组成。为了减小n包层和n势垒层的II类异质结处的异质结势垒，我们在异质结中引入了一种MgSe/ZnCdSe梯度SL结构。在梯度SL中，从n-包层到n-势垒一侧，沿生长方向，MgSe层厚度比从40%逐渐增加到60%。通过电流注入，我们观察到530 nm附近的绿色发射。通过对器件在直流注入下的老化试验，我们获得了超过4800h的长寿命运行，没有灾难性的退化。此外，我们还开发了新的p-包层材料。我们提出了一种新的掺杂技术，即在p掺杂较差的锌镉镉和镁硒/锌镉硒SL层中按一定的间隔插入高磷掺杂的ZnTe或ZnSeTe层，并通过实验证明了该技术对磷掺杂是有效的。例如，利用该技术，锌镉镉的p掺杂浓度由原来的约31016 cm-3显著提高到8×1017 cm-3。在MgSe/ZnCdSe SL的情况下，在2.33 eV的宽带隙处获得了高的p掺杂浓度4.6×1017 cm-3。将掺杂技术应用于p包层，制备了发光器件。因此，我们得到了600 nm左右的橙色发射。

We investigated Be composition dependencies of the luminescence property of BeZnSeTe II-VI compound semiconductors grown on InP substrates, resulting in obtaining bright luminescence in green region. Then we proposed a MgSe/BeZnSeTe superlattice(SL) barrier layer to confine carriers and optical field into the BeZnSeTe active layer, and improved the growth conditions such as the Zn irradiation at the SL interfaces. Based on these results, we fabricated light emitting devices. The device consisted of a BeZnSeTe quantum well active layer sandwiched by MgSe/BeZnSeTe SL barrier layers, MgSe/ZnCdSe SL n-cladding, and MgSe/BeZnTe SL p-cladding layers. In order to reduce the hetero barrier at the type-II hetero junction of the n-cladding and the n-barrier layers, we introduced a MgSe/ZnCdSe graded SL structure into the hetero junction. In the graded SL, the MgSe layer thickness ratio was gradually increased from 40 to 60 % along the growth direction from the n-cladding to the n-barrier side. By current injections, we observed green emissions around 530 nm. By aging tests of the devices under direct current injections, we obtained long life operations beyond 4800 h with no catastrophic degradation.In addition, we developed new p-cladding layer materials. We proposed a new doping technology that is inserting high p-doped ZnTe or ZnSeTe layers at regular intervals into ZnCdSe and MgSe/ZnCdSe SL layers which are inferior in p-doping, and experimentally proved the technology to be effective for p-doping. For example, the p-doping concentration of ZnCdSe which had been about 31016 cm-3 before was remarkably improved to be 8×1017 cm-3 using the technology. In the case of the MgSe/ZnCdSe SL, a high p-doping concentration of 4.6×1017 cm-3 was obtained at a wide bandgap of 2.33 eV. Applying the doping technology for the p-cladding layer, we fabricated light emitting devices. Consequently we obtained orange emissions around 600 nm.