Enhanced direct-gap light emission from Si-capped n+-Ge epitaxial layers on Si after post-growth rapid cyclic annealing: impact of non-radiative interface recombination toward Ge/Si double heterostructure lasers.
Enhanced direct-gap light emission from Si-capped n+-Ge epitaxial layers on Si after post-growth rapid cyclic annealing: impact of non-radiative interface recombination toward Ge/Si double heterostructure lasers.
复制标题
生长后快速循环退火后，Si 上硅覆盖的 n-Ge 外延层增强的直接间隙光发射：非辐射界面复合对 Ge/Si 双异质结构激光器的影响。
DOI：
10.1364/oe.25.021286
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发表时间：
2017
期刊：
影响因子：
3.8
通讯作者：
Y. Ishikawa
中科院分区：
文献类型：
--
作者：
N. Higashitarumizu;Y. Ishikawa
报道了硅覆盖的n+-Ge层在后生长快速循环退火(RCA)后的直接能隙发光增强，并讨论了Ge/Si界面的非辐射复合(NRR)对Ge/Si双异质结(DH)激光器的影响。用超高真空化学气相沉积的方法在硅上生长了掺磷的n+-Ge层(1×1019 cm-3,400 nm)，然后生长了5 nm的Si盖层，形成了Si/Ge/Si双异质结结构。为了消除Ge中的缺陷，生长后RCA是在氮气中进行的，温度在900℃到780℃之间，其中每个RCA循环的退火时间最短为5 S，以防止P掺杂从Ge表面向外扩散。在RCA循环至40次时，1.6µm处的直接带隙光致发光(PL)强度随RCA循环次数的增加而增加，但在本条件下，Ge中的丝状位错密度在3次循环后并未降低。发光的增强归因于Ge/Si界面对NRR的抑制，在那里形成了混合的SiGe合金。对于Ge/Si双异质结激光器，Ge/Si界面的NRR对阈值电流密度Jth有显著影响。为了获得1kA/cm~2量级的JTH，与III-V激光器类似，尽管在普通的富缺陷Ge/Si界面上，S的界面复合速度高达105 cm/S，但界面复合速度要求S低于103 cm/S。
Enhanced direct-gap light emission is reported for Si-capped n+-Ge layers on Si after post-growth rapid cyclic annealing (RCA), and impact of non-radiative recombination (NRR) at the Ge/Si interface is discussed toward Ge/Si double heterostructure (DH) lasers. P-doped n+-Ge layer (1 × 1019 cm-3, 400 nm) is grown on Si by ultra-high vacuum chemical vapor deposition, followed by a growth of Si capping layer (5 nm) to form a Si/Ge/Si DH structure. Post-growth RCA to eliminate defects in Ge is performed in N2 at temperatures between 900°C and 780°C, where the annealing time is minimized to be 5 s in each RCA cycle to prevent an out-diffusion of P dopants from the Ge surface. Direct-gap photoluminescence (PL) intensity at 1.6 µm increases with the RCA cycles up to 40, although the threading dislocation density in Ge is not reduced after 3 cycles in the present condition. The PL enhancement is ascribed to the suppression of NRR at the Ge/Si interface, where an intermixed SiGe alloy is formed. For Ge/Si DH lasers, NRR at the Ge/Si interface is found to have a significant impact on the threshold current density Jth. In order to achieve Jth on the order of 1 kA/cm2, similar to III-V lasers, the interface recombination velocity S is required below 103 cm/s in spite of S as large as 105 cm/s at the ordinary defect-rich Ge/Si interface.
影响因子：
3.8
作者：
Koerner, Roman;Oehme, Michael;Schulze, Joerg
通讯作者：
Schulze, Joerg