结电容对不同光敏元尺寸InGaAs探测器I-V特性测试的影响

Impact of Junction Capacitance on Measurement of I-V Characteristic of InGaAs Detectors with Different Photosensitive Element Sizes

摘要:  I-V特性是光伏探测器最重要的表征手段之一。用电压扫描方式对光敏元尺寸为Φ 5 mm的InGaAs探测器进行I-V测试时，在负压方向电流出现了震荡现象。分析认为采样时电压处在变化中，变化的电压会引起积累在P-N结空间电荷和扩散区电荷的改变，形成P-N结电容效应而导致。本文通过测试不同光敏元尺寸探测器的零偏电阻、暗电流和电容，讨论了光敏元尺寸对InGaAs探测器I-V特性测试的影响。结果表明：随着光敏元尺寸增大，探测器的零偏电阻减小，暗电流增大，电容增大。并分析了InGaAs探测器的P-N结电容效应及其对I-V特性测试的影响，当零偏压结电容C > 10⁻⁸f @2 kHz时，I-V特性曲线在负压方向电流出现了震荡现象，测试过程中可通过限流设置或从正偏压至反偏压测试两种方式避免电流振荡现象，实现大光敏元Φ 5 mm InGaAs探测器I-V特性测试。

Abstract: I-V is one of the most important means of characterization. In voltage scanning mode of Φ 5 mm InGaAs detector for I-V test, it showed current oscillation in direction of negative pressure. It is analyzed that the change of voltage will cause accumulation of space charge and charge junction diffusion region in the P-N change, forming a P-N junction capacitance effect, resulting in the cor-responding bias dark current superimposed on a current due to charge and discharge that the capacitor brings. In this paper, the zero bias resistance, dark current and capacitance of detectors with different photosensitive sizes are tested. With the increase of the dimension size of the photosensitive element, the zero bias resistance of the detector decreases, the dark current increases, and the capacitance increases. And the P-N junction capacitance effect of InGaAs detector and its influence on I-V characteristic test are analyzed. When the zero bias junction capacitance C > 10⁻⁸f @2 kHz, InGaAs detector I-V characteristic curve produces to oscillate in the negative voltage direction. I-V test of InGaAs detector with Φ 5 mm large photosensitive element can be realized by current limiting setting or testing from positive bias to negative to avoid current oscillation.