對於操作在大於25 Gbit/sec光波長範圍從0.85 μm到1.55 μm，我們提出新型有大主動區直徑的InP(磷化銦)光偵測器結構。在結構中0.85μm激發波長下，因為In0.53Ga0.47As有大的吸收常數(3 "μm-1" )，故P型In0.53Ga0.47As作為吸收層其且慢的電洞傳輸會被消除，由於RC限制頻寬和載子傳輸時間之間取得平衡，故(~4 μm)厚度In0.53Ga0.47As有著完美電子傳輸特性。此外，為了讓最上層P型In0.53Ga0.47As吸收層最大限度地減少嚴重的表面複合，故再P型In0.53Ga0.47As吸收層上加上一層P型In0.52AlxGa0.48-xAs漸變式摻雜層，漸變式摻雜層不僅能均勻吸收光，而且可以加快電子擴散。分別操作在波長0.85 μm到1.55 μm，偏壓-1V下，此元件實現了高速(14 和 22 GHz)和高響應度(0.25 和 0.9 A/W)。在兩個波長下,已證實資料傳輸高達30 Gbit/sec且清楚的看到眼圖(無誤碼）。 We demonstrate a novel InP based photodiodes structure with large active diameters (55 "μ" m) for > 25 Gbit/sec operations at the optical wavelengths which range from 0.85 to 1.55 μm. By utilizing the large absorption constant (>3 "μ" m-1) of In0.53Ga0.47As based p-type absorption layer under 0.85 μm wavelength excitation, the slow hole transport can be eliminated in our structure and the trade-off between RC-limited bandwidth and carrier transient time can be greatly released due to the excellent characteristics of electron transport in the intrinsic and thick In0.53Ga0.47As layer (~4 μm). Furthermore, in order to minimize the serious surface (absorption) recombination in the top p-type In0.53Ga0.47As absorption layer, an additional p-type In0.52AlxGa0.48-xAs graded bandgap layer (GBL) is grown above it. Such GBL can not only uniform the profile of photo-absorption but also accelerate the electron diffusion process. Under -1 V bias, these devices can achieve high-speed (14 and 22 GHz), and high responsivity (0.25 and 0.9 A/W), at 0.85 and 1.55 μm wavelength operation respectively. Clear eye-opening (error-free) with data rate up to around 30 Gbit/sec have also been demonstrated in both wavelengths.
