STTR Phase I: Metalorganic Chemical Vapor Deposition (MOCVD) Growth of GaAs Wafers for Heterojunction Bipolar Transistors with Reduced Burn-In

这项小型企业技术转移(STTR)第一阶段研究项目的目标是基于GaAs的异质结双极晶体管(HBT)的性能。这些异质结双极晶体管的高功率和高频特性导致它们被用作几种无线应用的功率放大器，例如蜂窝电话和无线局域网。在器件运行的最初几分钟，即所谓的老化，制作的HBT的增益增加了四倍之多。然后，在长达数十个小时的操作过程中，增益继续漂移，可以上下浮动。增益的漂移在功率放大器的设计和生产中需要大量的成本和资源。放大器电路必须能够适应晶体管增益的这些变化，这需要显著的性能折衷，从而导致电路开发和上市时间的额外成本。否则，单个设备必须经过广泛的测试才能实现稳定运行。虽然众所周知，但人们对老化和漂移现象知之甚少。需要改进的薄膜沉积方法来最小化老化和漂移。以前的调查已经将这些不稳定性与基座中的点缺陷联系在一起。由于功率放大器每年生产数亿个单元，延长老化测试是昂贵的，而且有必要避免。如果成功，用于功率放大器的低烧损异质结双极晶体管的开发将是一个重要的制造发展，因为它最终可以降低器件的成本。由于这些设备主要用于手机，对于发射机来说，实现低燃烧和漂移设备的制造方法将使消费者的成本更低。

This Small Business Technology Transfer (STTR) Phase I research project targets performance of GaAs-based heterojunction bipolar transistors (HBT). The high power and high frequency characteristics of these HBTs have led to their use as the power amplifier for several wireless applications such as cellular phones and wireless local area networks. The gain of a fabricated HBT increases by as much as a factor of four during the first few minutes of device operation, known as burn-in. The gain then continues to drift, which can be either up or down, over the span of tens of hours of operation. The drift in gain requires significant cost and resources in power amplifier design and production. The amplifier circuitry must be able to accommodate these variations in transistor gain requiring a significant performance compromise resulting in additional cost for circuit development and time to market. Individual devices must otherwise go through extensive testing to achieve stable operation. While well known, the burn-in and drift phenomena are poorly understood. Improved film deposition methods are needed to minimize the burn-in and drift. Previous investigations have linked these instabilities to point defects in the base.With power amplifier production at hundreds of millions of units annually extended burn-in testing is expensive and necessary to avoid. If successful the development of low burn in heterojunction bipolar transistors for power amplifiers will be an important manufacturing development since it can ultimately lower the cost of the devices. Since these devices are used primarily in cell phones, for the transmitter, accomplishing a manufacturing methodology for low burn and drift devices would result in a lower cost to the consumer.