Growth study of chemical beam epitaxy of GaNxP1−x using NH3 and tertiarybutylphosphine
Abstract A study in the growth of GaN x P 1 − x epilayers by chemical beam epitaxy using tertiarybutylphosphine (TBP), ammonia (NH 3 ), and elemental Ga or triethylgallium is reported. Monitoring reflection high-energy electron diffraction (RHEED) intensity oscillations, we observe that both group-III- and group-V-induced incorporation rates are increased when NH 3 is introduced into a single cracker with TBP. From the difference in the periods of group-V-induced RHEED intensity oscillations, a 16% N incorporation is expected, but X-ray rocking curve measurement shows only 0.08% N. Using separate TBP and NH 3 crackers results in no enhancement in incorporation rates. We conclude that the cracking efficiency of TBP is increased with NH 3 co-injection.
X-ray photoelectron spectroscopy study of GaN and GaP surfaces annealed in PH3 and NH3 and metalorganic chemical vapor deposition growth of GaN / GaP heterostructures
Abstract The annealing effects of GaN and GaP in PH 3 and NH 3 , respectively, are investigated, and metalorganic chemical vapor deposition (MOCVD) growth of GaP on GaN and GaN on GaP was performed. The following results are obtained: N atoms are introduced into GaP by the annealing in NH 3 at relatively low temperature of about 800°C and wurtzite-GaN crystal is formed. However, the GaN crystal quality is low and GaP is degraded. On the other hand, high temperature annealing is necessary to introduce P atoms into GaN by the annealing in PH 3 . The heteroepitaxy of hard GaN on GaP degrades substrate quality, and the reverse epitaxy, soft GaP on hard GaN substrate, is greatly influenced by the substrate quality.
Human reproduction: irrational but in most cases morally defensible
While I am inclined to agree that in most cases a choice to become pregnant and bring to birth a child is an irrational choice, unlike Professor Hayry,1 I believe that choosing to do so is far from being necessarily immoral. In fact I will argue that it is often these irrational (but morally defensible) choices which make human life the valuable commodity many of us believe it is.

Hayry argues that not only is the choice to have children always an irrational choice, but also it is necessarily an immoral choice. Thus, for Hayry “human reproduction is fundamentally immoral”.1 He claims it is important to point out to prospective parents that their urge to have children is irrational. From this, he argues, it follows that once this is accepted the use of advance technologies to assist conception should be reassessed, and furthermore, the irrationality and immorality of having children should become a legitimate part of guidance given to those expressing a wish to have children.

According to Hayry the reason it is irrational and immoral to choose to bring to birth a child is that “having a child can always realistically lead to the worse possible outcome, when the alternative is not having a child”.1 He argues that when people consider having children they are faced with the choice between deciding not to have children and thus harming or benefiting no-one (this, it is argued has a value of zero), or having children where this life may be good or bad, and thus the value of this choice can be …