Dark Current Characteristics of a Radiation Detector Array Developed Using MOVPE-Grown Thick CdTe Layers on Si Substrate

作者：Yasuda K^*; Niraula M; Fujimura N; Tachi T; Inuzuka H; Namba S; Muramatsu S; Kondo T; Agata Y

来源：Journal of Electronic Materials, 2012, 41(10): 2754-2758.

DOI：10.1007/s11664-012-2121-7

• Gamma-ray array
• CdTe epitaxial layers
• heterojunction diode
• dark current

We present reverse bias current (dark current) characteristics of a two-dimensional monolithic pixel-type nuclear radiation detector array fabricated using metalorganic vapor-phase epitaxy (MOVPE)-grown thick CdTe epitaxial layers on Si substrate. The (14 x 8) pixel array was formed by cutting deep vertical trenches using a dicing saw, where each pixel possesses a p-CdTe/ n-CdTe/n (+)-Si heterojunction diode structure. The dark currents showed pixel-to-pixel variations when measured at higher applied biases exceeding 100 V. The dark current had a dependence on the pixel thickness, where pixels with lower CdTe thickness exhibited higher currents. Moreover, the temperature dependence of the dark current revealed that a deep level with activation energy of around 0.6 eV is responsible for the observed dark currents and their pixel-to-pixel variation. We discuss that the effective ratio of Te to Cd at the growth surface is a major factor that controls the thickness variation, and is also responsible for the formation of 0.6 eV deep levels.

• 出版日期2012-10