In this article, a metal/carbon-doped GaN (GaN:C)/Si-doped GaN (GaN:Si) structure was used to investigate the defect characteristics and carrier transport mechanisms in GaN:C layers with different carbon doping concentration. Capacitance-voltage, current–voltage, and deep-level transient spectroscopy measurements were performed at different temperatures. At forward bias, a pinning effect was found at the interface of the GaN:C/GaN:Si layer, due to the defects capturing electrons. The forward currents of the samples with high carbon doping concentration ( ${N}_{C}> {1} \times 10^{{19}}$ cm⁻³) increase gradually with increasing forward bias voltage. Ohm’s law, space-charge-limited current, and variable-range-hopping mechanisms may dominate the forward current. For the samples with low carbon doping concentration ( ${N}_{C} < {1} \times 10^{{19}}$ cm⁻³), a device turning on behavior was observed, which is attributed to the carriers overcoming a potential barrier. In addition, the DLTS spectra reveal that only electron trapping happens at forward bias for the samples with high carbon doping concentration, while, in addition, hole trapping was observed for the samples with low carbon doping concentration. The process of the carrier capture by defects was demonstrated.

中文翻译：

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不同碳掺杂浓度GaN层缺陷特征及载流子传输机制研究

在本文中，金属/碳掺杂 GaN (GaN:C)/Si 掺杂 GaN (GaN:Si) 结构用于研究具有不同碳掺杂浓度的 GaN:C 层中的缺陷特征和载流子传输机制。在不同温度下进行电容-电压、电流-电压和深能级瞬态光谱测量。在正向偏压下，由于捕获电子的缺陷，在 GaN:C/GaN:Si 层的界面处发现了钉扎效应。高碳掺杂浓度样品的正向电流（ ${N}_{C}> {1} \times 10^{{19}}$ cm ^-3 ) 随着正向偏置电压的增加而逐渐增加。欧姆定律、空间电荷限制电流和可变范围跳跃机制可能主导正向电流。对于碳掺杂浓度较低的样品（ ${N}_{C} < {1} \times 10^{{19}}$ cm ^-3 )，观察到器件开启行为，这是由于载流子克服了势垒。此外，DLTS 光谱表明，对于具有高碳掺杂浓度的样品，仅在正向偏压下发生电子捕获，而对于具有低碳掺杂浓度的样品，观察到空穴捕获。演示了通过缺陷捕获载流子的过程。