In this work, the p-type doping of the S A type stepped Ge(100) surface by a diborane ( B 2 H 6) gas flow has been simulated by the possible dissociation and adsorption models. The most probable dissociation model of B 2 H 6 and adsorption models of the fragments of B 2 H 6 on the stepped Ge(100) surface have been determined by the local minimum total energy and/or binding energy calculations based on the Density functional (B3LYP/6-3g) and Hartree–Fock (HF/STO-3g) theories, respectively. The present calculations have shown that, the step region (for both up and down terraces) of the stepped Ge(100) surface has the most attractive sites for BH3 molecules determined to be the first dissociation fragments of B 2 H 6 by an external energy of ~ 1.3 eV. It has been found that, at the first step of the adsorption, BH3 can dissociate to BH2 and BH fragments on the stepped Ge(100) surface. While BH3 and BH2 products prefer to be attached to a single surface Ge atom, BH is bridged between two adjacent surface Ge atoms. According to the present optimization calculations, the p-type doping process of the stepped Ge(100) surface has started with the adsorption of BH3 on the electron deficient site (buckled down) of the Ge dimer bond close to the step edge and ended with the substitutional occupation of the Ge site in the layers of the surface by B atom. The beginning of the p-type doping of the stepped Ge(100) surface has been illustrated by the electronic states of B appeared in the optical energy gap of Ge very close to the edge of the HOMO.

The most stable structures for the adsorption and dissociation of phosphine (PH 3 ) on SiGe(100) (2 × 1) surface have been investigated by relative total energy calculations based on density functional theory. According to the optimization calculations, PH 3 is adsorbed on the Si (down) and Ge (down) site of the Ge-Si and Ge-Ge dimers on SiGe surface, respectively. The PH 2 and H products have been found to be thermodynamically favored in the dissociation path of PH 3 on SiGe surface when the system is thermally activated. Although PH 3 is adsorbed on the Ge-Ge and Ge-Si dimers directly, it dissociates on the SiGe surface by passing through a transition state. The asymmetric Ge-Si and Ge-Ge dimers on SiGe surface are found to be approximately symmetric after the dissociation of PH 3 on the surface. The present work has showed that PH 2 prefers to be adsorbed on Ge site of the Ge-Si dimer. Therefore, the adsorption of PH 2 on Ge site of the Ge-Si dimer, while PH 3 being dissociated on the Si site, has indicated the migration of PH 2 on SiGe surface.

1929 yılında yaşanan Büyük Buhran yaklaşık on yıl boyunca Amerika Birleşik Devletleri başta olmak üzere bütün dünyayı etkilemiştir. 24 Ekim 1929 Perşembe günü Amerikan borsası dibe vurur. Bu sebeple bu tarih Kara Perşembe olarak anılır. Krizin yansımaları toplumun her kesiminde derinden hissedilir. Yüz binlerce insan işini ve evini kaybeder. Tarım ürünü fiyatlarında çok ciddi düşüşler yaşanır. Çiftçiler bu süreçte büyük mağduriyetler yaşarlar. Birçok banka kapanır ve toplumda büyük bir kaos oluşur. Dönemin genel havasına bakıldığında bu krizin birçok alanda etkisini gösterdiği söylenebilir. Sanat ve edebiyat da bu alanlar arasındadır. Büyük Buhran, Amerikalı yazar John Steinbeck'in Gazap Üzümleri romanına da konu olmuştur. Gazap Üzümleri romanı, Büyük Buhran sürecini çiftçi bir ailenin yaşam mücadelesi üzerinden ele alır. Romanda kuraklık, işsizlik, göç, mülteci olma durumu, ötekileştirilme, işçinin sömürülmesi, açlık, sefalet ve daha birçok mesele Joad ailesi üzerinden verilir. Bu çalışmada iktisadi bir bakışla Büyük Buhran'ın Gazap Üzümleri romanına yansıması ele alınmıştır. Romandan hareketle dönemin iktisadi durumu roman kurgusu üzerinden değerlendirilmiştir.