Depth Profiling of Ion Beam Induced Damage in Semiconductor Heterostructures
- PDF / 361,104 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 96 Downloads / 214 Views
DEPTH PROFILING OF ION BEAM INDUCED DAMAGE IN SEMICONDUCTOR HETEROSTRUCTURES R. GERMANN*, A. FORCHEL*, G. HORCHER* AND G. WEIMANN** *4. Physikalisches Institut, Universitat Stuttgart, Pfaffenwaldring 57, D-7000 Stuttgart 80, Federal Republic of Germany **FTZ der Deutschen Bundespost, Am Kavalleriesand 3, D-6100 Darmstadt, Federal Republic of Germany. Present adress: TU Munchen, Walter Schottky Institut, Am Coulombwall, D-8046 Garching, Federal Republic of Germany ABSTRACT We have produced beveled cross-sections of GaAs/GaAlAs multiple quantum well structures with inclination angles of 0.55 minutes of arc with a special ion beam etching technique. The extension of the damage which is induced during the dry etching process can be evaluated directly by a comparison of spatially resolved secondary ion mass spectroscopy and photoluminescence measurements. We observe a thickness of the damaged surface layer between 36 nm for 250 eV Argon ions and 160 nm for 1000 eV Argon ions in a GaAs/GaAlAs multiple quantum well structure. INTRODUCTION Ion assisted dry etching techniques are commonly used for the fabrication of semiconductor microstructures with lateral dimensions below 1 micron. The advantages of these techniques are the anisotropic etching characteristic and the good reproducibility [1]. The most significant drawback of these methods is the induced etching damage, which is caused by the ions used with typical energies of a few hundred electron volts. The damage can be described by an amorphous surface-near region and an implantation of ions in deeper regions of the samples. The range and the depth distribution of the created damage is of fundamental interest, because it is the limiting factor for device fabrication by dry etching. Surface damage plays a more and more critical role if the dimensions of microstructures are reduced, because of the increasing ratio between surface and volume. The electrical and optical properties of dry etched devices depend strongly on the induced damage. Some results have been reported recently for GaAs. Scherer et al. [2] determined the damage depth from the I-V characteristic of Schottky contacts on a GaAs surface etched by ion beam etching. The fabrication of the Schottky contacts is generally a critical step and the determination of the damage depth is indirect. Yuba et al. [3] made DLTS measurements on dry etched GaAs samples. The depth distribution of different defects could be revealed after a low temperature annealing. In this case a Schottky contact is also necessary. Both authors report damage depths far beyond the ion range calculated with standard LSS theory [4]. We present a method which shows directly the extension of the damage in ion beam etched samples without any treatment (as evaporation or annealing) of the samples after the etching process. The method is based on the fabrication of a bevel with an inclination angle below one minute of arc by an ion beam etching process with a special etching geometry and subsequent spatially resolved measurements with secondary ion
Data Loading...
