ErAs:In(Al)GaAs photoconductors have proven to be outstanding devices for photonic terahertz (0.1–10 THz) generation and detection with previously reported sub-0.5 ps carrier lifetimes. We present the so far most detailed material characterization of these superlattices composed of ErAs, InGaAs, and InAlAs layers grown by molecular beam epitaxy. The variation of the material properties as a function of the ErAs concentration and the superlattice structure is discussed with focus on source materials. Infrared spectroscopy shows an absorption coefficient in the range of 4700–6600 cm${}^{-1}$ at 1550 nm, with shallow absorption edges toward longer wavelengths caused by absorption of ErAs precipitates. IV characterization and Hall measurements show that samples with only 0.8 monolayers of electrically compensated ErAs precipitates (p-delta-doped at $5\times {10}^{13}$ cm${}^{-2}$) and aluminum-containing spacer layers enable high dark resistance ($\sim 10$–20 M$\mathrm{\Omega }$) and high breakdown field strengths beyond 100 kV/cm, corresponding to $>500$ V for a 50 $\mu$m gap. With higher ErAs concentration of 1.6 ML (2.4 ML), the resistance decreases by a factor of $\sim 40$ (120) for an otherwise identical superlattice structure. We propose a theoretical model for calculation of the excess current generated due to heating and for the estimation of the photocurrent from the total illuminated current. The paper concludes with terahertz time-domain spectroscopy measurements demonstrating the strengths of the material system and validating the proposed model.

中文翻译：

---

用于1550 nm激光操作的ErAs：In（Al）GaAs光电导体的材料特性和性能

业已证明ErAs：In（Al）GaAs光电导体是光子太赫兹（0.1-10 THz）产生和检测的杰出器件，以前报道的载流子寿命低于0.5 ps。我们介绍了到目前为止由分子束外延生长的ErAs，InGaAs和InAlAs层组成的这些超晶格的最详细的材料表征。讨论了材料属性随ErAs浓度和超晶格结构的变化，重点是源材料。红外光谱显示的吸收系数在4700-6600 cm范围内${}^{-\mathrm{1个}}$在1550 nm处，由ErAs的吸收引起的浅吸收边缘朝向更长的波长沉淀。IV表征和霍尔测量表明，只有0.8个单层电补偿ErAs沉淀的样品（p-delta掺杂在$5\times {10}^{13}$ 厘米${}^{-\mathrm{2个}}$）和含铝的隔离层可实现较高的耐暗性（$〜10$–2000万$\mathrm{\Omega }$）和超过100 kV / cm的高击穿场强，对应于 $>500$ V代表50 $\mu$米的差距。随着较高的ErAs浓度1.6 ML（2.4 ML），电阻降低了$〜40$（120）对于其他相同的超晶格结构。我们提出了一个理论模型，用于计算由于加热而产生的过电流，并根据总照明电流估算光电流。本文以太赫兹时域光谱测量为结束，论证了材料系统的优势并验证了所提出的模型。