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以外延Ge薄膜为吸收区,在Si基上制备了Ge波导光电探测器。利用超高真空化学汽相淀积(UHV/CVD)设备,采取低温高温两步法,在Si(100)衬底上外延出厚度约为500nm的高质量纯Ge层。探测器采用脊型波导结构,Al电极分别制作在波导的台面上下形成背对背肖特基结。I-V特性测试表明,在-1V偏压下,暗电流密度为0.2mA/cm2。由于Si与Ge热失配引起外延的Ge薄膜受到0.2%张应变,减小了Ge带隙,光响应波长范围扩展到1.60μm以上。在70mW、1.55μm入射光照射下,测得光电流比暗电流高出近1个数量级。
Ge epitaxial Ge film as the absorption region, prepared on the basis of Ge-based Ge waveguide photodetector. A high-quality pure Ge layer with a thickness of about 500 nm is epitaxially grown on a Si (100) substrate by a two-stage cryogenic high temperature process using an ultrahigh vacuum chemical vapor deposition (UHV / CVD) apparatus. The detector adopts a ridge waveguide structure, and Al electrodes are respectively fabricated on the top and bottom of the waveguide to form a back-to-back Schottky junction. The I-V characteristic test showed that the dark current density was 0.2 mA / cm2 at -1 V bias. Due to the thermal mismatch between Si and Ge, the epitaxial Ge film is subjected to 0.2% strain and the Ge bandgap is reduced. The wavelength range of photoresponse is extended to over 1.60μm. Under 70mW and 1.55μm incident light, the photocurrent was found to be nearly one order of magnitude higher than the dark current.