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在一个垂直浸渍系统中使用经过改进的过补偿方法能重复地生长高效率的发射绿光的GaP p—n结材料,把它做成块状的无接触的二极管,在空气中,当电流密度为7A/cm~2时其平均量子效率高达0.101％。它相当于平均效率为0.16％的环氧树脂封装的台面二极管,而后者已比老产品提高了60％。用我们的材料制成的台面二极管的效率当电流密度为5A /cm~2时高达0.23％,而在～300A/cm~2时竟达0.67％。这里低电流时的效率值高于已报导的任何数值,而高电流密度的效率与已报导的最高值相同。效率的提高是在以前的过补偿生长方法中引进了某些革新而获得的。其中最要重的改进是采取从900℃到700℃的大冷却区间,相应地降低了 p—n结形成的温度(850℃),这样就使效率得到提高。少数载流子寿命的测量结果揭示了少数载流子在n型层和p型层中寿命的空间变化。寿命随着生长温度降低而增加表明这种LPE生长温度应该尽可能的低。典型值是结中的τ_h=200毫微秒和τ_e=100毫微秒。从LPE生长系统排出的气体的分析估计,在这种 LPE生长系统中一般含有多达～5 ppm的氧。在输入气体中掺入>10ppm的少量氧,就会引起量子效率和少数载流子寿命显著地降低,而氧的含量≤10ppm时,效率或寿命不受影响。
High efficiency green-emitting GaP p-n junction material can be repeatedly grown using a modified overcompensation method in a vertical dip system to make a blocky, contactless diode in air with a current density The average quantum efficiency of 7A / cm ~ 2 is as high as 0.101%. It is equivalent to an epoxy encapsulated mesa diode with an average efficiency of 0.16%, which is up 60% over the older product. The efficiency of mesa diodes made with our materials is as high as 0.23% at current densities of 5 A / cm2 and 0.67% at ~ 300 A / cm2. The efficiency value at low current here is higher than any reported value, whereas the high current density is the same as the highest reported value. The improvement of efficiency was obtained by introducing some innovations in the previous overcompensation methods of growth. One of the most important improvements is the adoption of a large cooling zone from 900 ° C to 700 ° C, which in turn reduces the temperature at which the p-n junction is formed (850 ° C), thus increasing efficiency. The measurement of minority carrier lifetime reveals the spatial variation of minority carriers’ lifetime in n-type and p-type layers. The increase in longevity as the growth temperature decreases indicates that this LPE growth temperature should be as low as possible. Typical values are τ_h = 200 ns and τ_e = 100 ns in the junction. Analysis of the gases exiting the LPE growth system estimates that up to ~ 5 ppm of oxygen are typically contained in this LPE growth system. Incorporating a small amount of oxygen at> 10 ppm into the input gas results in a significant decrease in quantum efficiency and minority carrier lifetime, while efficiency or lifetime is unaffected when the oxygen content is <10 ppm.