氧離子佈植與低溫成長砷化鎵光導天線在連續波與脈衝波激發下產生兆赫波的研究

Abstract

本論文討論在多重氧離子佈植砷化鎵 (2.5 X 10^13 ions/cm^2 (500 keV & 800 keV ), (1200 keV) 薄膜材料及低溫成長之砷化鎵在脈衝波與連續波的激發下比較其兆赫波的特性。 多重氧離子佈值砷化鎵偶極天線在脈衝雷射與連續波雷射激發下都具有較高的兆赫波輻射功率，以180mW連續波雷射激發時多重氧離子佈植砷化鎵天線輻射功率(2.27uW)大約比同結構的低溫成長砷化鎵（1.27uW）高。以30mW的脈衝光雷射激發時，多重氧離子佈植砷化鎵天線輻射功率(5.2mW)大約比同樣結構的低溫成長砷化鎵天線產生（3.6mW）高。另外多重氧離子佈值砷化鎵與低溫成長砷化鎵偶極天線在連續波與脈衝波激發下測量其頻寬皆可達1THz。然而，低溫成長砷化鎵光導天線在連續波的激發下產生飽和的現象，多重氧離子佈值砷化鎵光導天線仍然沒有，因此多重氧離子佈值砷化鎵光導天線具有較好的兆赫波輸出功率。

THz wave was generated from dipole antenna-type devices made by using oxygen-ion implanted GaAs (GaAs:O) and low-temperature-grown GaAs (LT-GaAs). We compared the emission properties of LT-GaAs photoconductive (PC) antennas with GaAs:O fabricated condition (2.5 X 10^13 ions/cm^2 (500 keV & 800 keV ), 4 X 10^13 ions/cm^2(1200 keV ) in the pulse and CW mode. The absolute power of THz wave was also measured by a bolometer for comparison of the relative radiation power. Compared GaAs:O with LT-GaAs at same structure of PC antennas. The material GaAs:O can generate higher THz power than LT-GaAs both in pulsed mode and CW mode. The THz power of GaAs:O (2.27uW) is higher than that of LT-GaAs(1.27uW) in CW mode, and in pulse mode, the THz peak amplitude of GaAs:O (5.2mW) is higher than that of LT-GaAs (3.6mW). The bandwidth of GaAs:O and LT-GaAs are measured about 1THz both under pulse (TDS) and CW (photomixing) pumping. However, the THz power of LT-GaAs is saturated on CW mode, while GaAs:O doesn’t. The result shows that GaAs:O is a proper THz emitter compare with LT-GaAs which is hardly to reproduce.