论文部分内容阅读
改进的里德型低-高-低高效率砷化镓崩越二极管的研制需要特殊的生长技术,即薄层(100～1000埃)能可控生长以及 n 型杂质浓度高度准确。为满足这一需要,设计了一个适用于标准的化学汽相淀积设备的气体掺杂剂注入系统。为了掺 n~+层,将准确计量好的硫化氢量瞬时释放造入气流中,它通过正在生长的外延层并部份掺入该层中。n~+层的参数控制为:宽±8%,位置±10%,杂质量±18%。这说明掺硫层的宽度是由1)实验的几何尺寸,2)气体流速,3)气体扩散和4)生长适率来决定的。硫的掺入正比于注入硫化氢的克分子数并随(生长速率)~(1.6)进行变化。生长之后固体中扩散的研究表明:高掺杂层的宽度展宽了,与砷化镓中硫的扩散系数D_G~S_(aAs)(750℃)=2×10~(-15)厘米~2/秒是一致的。掺杂技术得到气相与固相之间硫的分配系数的首次试验测量数值。分配系数定义为:K=(〔S~+〕P_H2))/((N_sP_(H2S))在我们的实验条件下,其值在13至16的范围内。研究表明外延层薄至150埃时,注入掺杂系统可使杂质浓度的控制服从于理想气体定律。更进一步地证明了生长速率的控制对掺杂控制来说是头等重要的。以后在改进掺杂控制方面的研究应集中在影响生长速率的各个变量上。
The development of an improved Reed low-, high-, and low-efficiency gallium arsenide collapse diode requires special growth techniques that allow controlled growth of thin layers (100-1000 angstroms) and high n-type impurity concentration. To meet this need, a gas dopant injection system has been designed for use with standard chemical vapor deposition equipment. In order to incorporate the n ~ + layer, an accurately measured amount of hydrogen sulfide is momentarily released into the gas stream, which passes through the growing epitaxial layer and partially into the layer. The n ~ + layer parameters are controlled as follows: ± 8% wide, ± 10% of position, and ± 18% of impurity. This shows that the width of the sulfur-doped layer is determined by 1) the experimental geometry, 2) the gas flow rate, 3) the gas diffusion and 4) the growth rate. The incorporation of sulfur is proportional to the mole fraction of hydrogen sulphide injected and varies with (growth rate) ~ (1.6). The study on the diffusion in solid after growth shows that the width of highly doped layer broadens, and the diffusion coefficient of sulfur in gallium arsenide is as follows: D_G ~ SAs (750 ℃) = 2 × 10 ~ (-15) cm ~ 2 / The second is the same. The doping technique yields the first experimental measurement of the sulfur partition coefficient between gas and solid phases. The partition coefficient is defined as: K = (S ~ +) P_H2) / ((N_sP_ (H2S)) Under our experimental conditions, the values range from 13 to 16. Studies have shown that when the epitaxial layer is as thin as 150 angstroms , The doping system can make the impurity concentration controlled by the ideal gas law.It is further proved that the control of the growth rate is of paramount importance to the doping control.Afterwards, the research on improving the doping control should focus on the influence Growth rate of the various variables.